The top and bottom albums are fixed, while the ones in the middle are much more relative and change their spots quite frequently.
Now, before I start giving my explanations I want to make clear that none of the albums are bad in my opinion. Maiden are by far my favorite band and even if some of my criticisms might come across as severe, I'd take most of Maiden's output over most albums by other bands. That said, there is a handful of songs that I truly despise, but more on that later. Starting from the bottom:
17.Killers: The artwork is iconic, the production much better than the debut. It features some great songs (the former B-side Twilight Zone is underrated as hell), but it is also the closest we've gotten to a filler album, which makes sense considering the background that the best songs were chosen for the debut and the "rest" was compiled for this one. Many of the songs are blatantly unfinished, repeating the same verses over and over again, Another Life being the worst offender with its single verse.
16.Iron Maiden: In some ways the reverse of Killers. Never liked the original cover (the 98 one is a bit better), the production is much weaker, but the songs themselves are stronger. Or at least some of them are. The old Maiden stuff isn't bad, but it's not really my type of music. I guess the early days of Heavy Metal just aren't really "metal enough" for me yet. Transylvania and POTO are fantastic songs, Remember Tomorrow a very interesting half-ballad, Prowler a good rocker, despite the cringeworthy lyrics. That's actually something a lot of the early Maiden material is suffering from. Can't really appreciate the middle section of Charlotte The Harlot heh with lyrics as bad as these.
15.The Final Frontier: The first "outlier" in the lower ranks, TFF was probably my biggest disappointment on a first listen for a Maiden album. The production and a lot of the performances are nice, the cover is weird and I don't hate it (though the perfectly horizontal key looks far too goofy, kinda ruining the whole thing) and there are definitely some strong moments. Overall there are too many weak songs on here for me. El Dorado is okay, Mother Of Mercy nothing special, Coming Home has fantastic verses but I kinda dislike everything else about it. Never liked the main (clean) riff for Isle Of Avalon and it repeats for literal minutes. The Man Who Would Be King feels unfinished and hastily pasted together. The Alchemist ist actually a fantastic rocker, but I keep forgetting that it exists. The Talisman, WTWWB and Starblind are all awesome though. From here on in my list there will be individual songs that might be better than most songs of other albums, but not good enough to elevate the whole album.
14.The Number Of The Beast: Going back to the older stuff, some of the biggest classics originated here. TNOTB and RTTH are good songs, but I've heard them so much that they aren't really special. Most songs are decent, but I vastly prefer almost everything that came after this album. 22AA and HBTN are the highlights, Invaders sucks and if we include Total Eclipse the rating gets dragged down even further. Total Eclipse is one of the few songs I genuinely despise and it's one of the 3 worst songs Maiden have ever written.
13.Piece Of Mind: The old style is getting closer and closer to the things I truly enjoy about Maiden. The production is quite weak in my opinion, but Bruce delivers some of his best vocal performances of his career. I'm generally not the biggest fan of young Bruce, because while his vocals were impressive, he had little control over them, constantly overshooting the actual pitch he was going for. His golden age was 1995 - 2008-ish. As far as songs are concerned this album is a mixed bag. Revelations, DWYBO, The Trooper, Still Life and QFF (yup, it's a 9/10 for me) are excellent, WED is quite boring for the most part, FOI is much better live, though those versions lack the great vocal harmonies. I never liked Sun And Steel and TTAL and they definitely drag the album down.
12.Somewhere In Time: This is one of those albums that I want to adore, but the material never really won me over. The artwork, the atmosphere, the sound; everything is captivating. TLOTLDR is one of the best songs of the entire decade, Deja Vu is a great rocker. HCW's middle section features some fantastic flourishes by Adrian. CSIT and ATG are legendary songs, though a bit weaker than TLOTLDR in my view. Wasted Years is nothing special, SOM and SIASL are weak but both feature strong solos by Adrian.
11.The X Factor: This album is full of potential, held back by a myriad tiny things that quickly add up. The production lacks depth and power, the performances should've gotten a few more takes, especially Blaze's vocals. I like his voice a lot and he's become a fantastic singer nowadays, but he wasn't there yet back then. The songs I don't like as much are Look For The Truth (the "whoah" part is quite repetitive and annoying, which is unfortunate since the verses are great) and 2 AM (which features far too mundane lyrics; the topic is alright, how it's dealt with isn't). SOTC gets the recognition it deserves, but LOTF, The Aftermath, and The Edge Of Darkness are all fantastic songs that are quite underrated.
10.Powerslave: This is a weird one for me. 2MTM is a timeless classic, and the title track is a highlight of their career. Those are the only two songs I adore. Losfer Words is quite good and probably the best instrumental, ROTAM is nice enough but incredibly overrated in my opinion. For me it's actually one of the weaker epics overall. FOTB and BITV have some great parts, but aren't necessarily amazing songs. The Duellists is similar, but I find the way the backing vocals sound in the chorus annoying and Bruce sings in an obnoxious register. Then there's Aces High, which I only ever liked in the studio version and even then it's next to impossible to sing properly. All of this sounds rather negative, yet PS is relatively high on my list. Why? Because of the fantastic guitar work. The layering of lead guitars on this album is unmatched and elevates the album a few spots.
09.No Prayer For The Dying: I know this is an unorthodox placement, but it's quite a consistent album. Unfortunately it doesn't have a proper epic, with Mother Russia being the one that comes closest. Some of the lyrics are cringe-worthy again (I'm looking at you Tailgunner), but there are many moments of brilliance spread all over the album. The title track is a strong half ballad with beautiful melodies, PENO is a fantastic rocker despite the pun in the name, Fates Warning has a weak intro but the rest of the song delivers; in contrast the intro to The Assassin has always been one of my favorite Maiden moments, but the rest of the song fails to deliver.
08.The Book Of Souls: While I absolutely hate Speed Of Light with every fiber of my being (another of the bottom 3 worst songs), there's a lot to love about that album. The title track is fantastic, the latter half of TRATB is pure Maiden magic, EOTC could've used some editing but is a fascinating moment in Maiden's career. WTRRD and SOTV are severly underrated, IESF should've had a different outro. DOG isn't really my favorite (I don't mind the lyrics, but the music isn't as exciting as it could be), TMOS is rather weak as well, but all in all this album was much more to my liking than TFF was.
07.Senjutsu: Another step up. Senjutsu might be one of the weakest title tracks; it's an interesting piece, but far too long without any real variation to be interesting enough for such time frames. Darkest Hour has nice music but horrible lyrics. As someone who loves The Clansman and was looking forward to DOTC, it was disappointing and is my least favorite song. I like that Bruce sings mostly in his lower register, but the song feels unfinished. It doesn't help that some of the production choices are questionable at best (the clean sound after the solos sounds like a pure DI). Other than that, the rest of the songs range from good (TWOTW) to great (TP, TTM, DOFP), to fantastic (Stratego, LIALW, HOE). Both TBOS and SNJ Eddies have been fantastic, but I really wish the next album artwork to have a proper background again.
06.Brave New World: The twin of VXI. In my opinion no other pair of albums is as close to each other as far as songwriting is concerned, as VXI and BNW are (except maybe the Iron Maiden - Killers pair). A good chunk of the songs were reused ideas from the VXI era and the general songwriting approach is incredibly similar. What helps BNW is that the production is much better, the performances are fantastic, and obviously the return of Bruce and Adrian. I used to adore The Nomad, but since finding out about the plagiarism and its best part being a glorified cover, it's fallen a lot in my rankings. The "whoah" part in Dream Of Mirrors, especially the live version, is perfection. The album is filled with interesting harmonies in the background vocals (the chorus to the radio version of Wicker Man, which is my preferred version; the chorus to OOTSP; the chorus in TTLBLAH as well as the second "I will live forever" part), something Bruce did in his solos albums as well. DOD has some of those as well, but it's something that basically disappeared over the years again, unfortunately.
05.Fear Of The Dark: Entering the top 5, we're starting with a very unorthodox choice. Yes, Bruce's vocals are different and not as interesting and impressive as the 80's and 2000's. Yes, The Apparition sucks. But damn, if the rest of the album isn't filled with gems. FOTD is an obvious classic, Childhood's End one of my absolute favorite Maiden songs. FHTE, COM and Weekend Warrior (not trolling, I swear) are pure, dumb fun. The Fugitive, JBMG, Wasting Love and ATSS are filled with great melodies. BQOBD is one of the most aggressive Maiden songs. Even FITK has a fascinating middle section. The production has a very unique sound that I've grown to love. The only downside for me is The Apparition; the rest of the album is great and gets far too much hate in my opinion.
04.Dance Of Death: For the longest time I used to prefer BNW to DOD, but a few years ago I realized that I actually enjoy this one more. Wildest Dreams is a boring rocker with an amazing slow section after the solos. Montsegur is the perfect example of wasted potential: Some of the heaviest riffs coupled with amazing melodies ruined by sections that wouldn't be out of place in children's songs. Then we also have Paschendale, which like Rime, is incredibly overrated for me. I love the tapping intro, the lyrics are beautiful, but the music never made an impression of me and I simply can't see what others see in this one. The rest of the songs are great. Rainmaker is one of their best rockers, NML and DOD are Maiden epics at their best. Gates Of Tomorrow is filled with great melodies and vocal harmonies. Age Of Innocence is amazing if you ignore the lyrics. Just wish it had the production of BNW and a better album cover.
03.Seventh Son Of A Seventh Son: Entering the top 3, we've got my favorite 80's album. The only track that I don't adore on this album is OTGDY and that's only because I'm not a fan of the chorus. Its verses are mesmerizing. CIPWM seems to get a lot of hate, even though it's such a fun song. The Prophecy ends with two fade-outs in a row and though I usually hate fade-outs, the material here is so strong that I can forgive them. The title track is epic the whole way through and the last minutes are pure magic. It managed to make the atmospheric middle section right, in contrast to ROTAM where I found it quite boring.
02.A Matter Of Life And Death: One of the most consistent albums of their entire career. Not a single bad song. Great experimentation with song structures, without going too far like they eventually did on TFF. It's kinda funny that out of ten songs, every single song except the last start in the same key, giving the whole thing a bit of a samey feeling. Bruce is still in fantastic shape, every other member provides incredibly strong performances as well. Thankfully the album sounds much better than DOD did.
01.Virtual XI: No, I'm not trolling. Yes, nostalgia is a huge factor for this ranking. Let's get the obvious out of the way: The production sucks and I can admit that there's a bunch of repetition on the album. That said, I don't mind the repetition at all. TAATG is the worst offender, but even though the chorus get's repeated and repeated and repeated and repeated and repeated and repeated the dynamics and even the chord progression change throughout the song. It's more than most repetitive Harris songs can claim. Blaze has played a bunch of songs with his solo band, with heavier production and even a harmony guitar for Futureal, showing the potential in these songs. This album features my absolute favorite Maiden song, Don't Look To The Eyes Of A Stranger. It plays around with tempo and dynamics and it's a shame that it got dropped from the VXI tour. I genuinely believe that a lot of these songs have the potential to come across great in a live setting, like The Clansman has for example. Give the material to the current line-up and to Bruce, who is a master at crowd control, and let them work their magic. The long build up in DLTTEOAS explodes into one of the most unique sections of a Maiden song, with frantic melodies and a polka-like drum rhythm. The only thing that's silly is the ending of the song.