Here is my ranking:
1. Brave New World
This album doesn't have a single weak track. and it's not like they are merely good either, most of them are absolutely amazing. Ultimately a pretty easy choice for 1st. It's extremely consistent too, I wanted to list the songs I like the most from it, but since I was basically writing out the whole album I'll leave it at that.
2. Seventh Son of a Seventh Son
It's a bit hard to rank Seventh Son against some the post reunion albums, because of the difference in length, but SSOASS is kind of like Brave New World's pre-reunion counterpart in that it nearly doesn't have weak tracks (I don't care for Moonchild that much which is why BNW still takes the top spot). Funnily enough, this album is so loaded that one of its most well known song (CIPWM?) and a huge maiden's classic is probably one of the "worst" track on the record.
3. Senjutsu
It seems like this is where it lands. Mainly because its top 3 songs (The Parchment, Senjutsu and Hell on Earth) are insanely good and could easily compete with the top 3 songs of the albums above it. The middle part of the album in still very strong (less than BTW and SSOASS still), and there is really only 2 songs that I feel are forgettable (Time Machine and TWOTW).
Lost in a Lost World is a song that upon the first listen I didn't enjoy very much, but now think it is great.
4. A Matter of Life and Death
I love AMOLAD, and didn't think I would be putting it below Senjutsu, but once I compared the tracks, I felt Senjutsu had just a slight edge. It also has 2 songs I don't care too much about (Pilgrim and Lord of The Flies).
I think even though AMOLAD has a bit more depth than Senjutsu and is consistently great, it doesn't get quite as good as Senjutsu's top 3, which is why I ultimately decided to rank it 4th.
5. The Book of Souls
The Book of Souls has my favourite Maiden song ever in Empire of the Clouds, another truly great song in its title track, and even though I know a lot of people dislike it, The Man of Sorrows is a song I absolutely adore.
If Eternity Should Fail and Shadows of the Valley (a track I re-discovered recently) round up a very strong top half. After that, the record runs out of steam a little bit. The Red and the Black and The Great Unknown are still nice, Death or Glory, Tears of a Clown and When the River Runs Deep are an occasional listen, However, I very much dislike Speed of Light.
This weaker bottom half is what prevents TBOS for climbing higher than 5 in my ranking.
6. Somewhere in Time
Similarly to SSOASS, It was tricky to rank it among the longer post-reunion album. I love Alexander the Great, The Loneliness, Wasted Years, and I'm probably a bigger fan of Déjà-Vu than most. However, the 4 other tracks clearly aren't as good as SSOASS "worst" 4s, and Ultimately the 6th place is where it feels right for Somewhere in Time
7. The Final Frontier
The Final Frontier is a great album, and it's a bummer that a lot of people don't seem to appreciate it. It maybe doesn't quite have the highs of some of the albums ranked above, and have 3 or 4 "meh" tracks, but it really has a lot of great stuff to offer. Comming Home, Starblind and The Talisman are incredible tracks, and TMWWBK/WTWWB is a wonderful way to close the album. If you have written this album off, give it another try.
8. Dance of Death
My least favourite of the post-reunion albums is still a good one, but not quite the level of the others. Yes, Paschendale and Dance of Death are amazing, and it has some other nice songs (The last 3, mainly), but about half of the record is filled with very forgettable songs, which is why it falls to the 8th place
9. Piece of Mind
It's kind of similar to DoD in that I don't really care for half of the tracks on there. The first 3 tracks are very good, but then it really slows down. I do like Quest for Fire more than most however, the bass line is really cool.
10. The Number of the Beast
What, 10th, how dare you ? It's classic ! Yes. I know. Hallowed, Children of the Damned and the title track are great, Run to the Hills I guess has its moments, but the truth is that I really don't care for the rest. So for me, the good is really good, but it's barely half the album, which is why I can't put it higher.
11. Fear of the Dark
Not sure what they did with this one, but there's a lot of tracks on this record that I'm not sure I would label as Heavy Metal... And then there's Weekend Warrior, which is IMO the worst track Bruce has done with Iron Maiden.
Thankfully There are a few truly amazing gems hidden between the bad songs, and a couple more of nice tracks, that prevent FotD from falling even lower.
12. Powerslave
Yes. I do not like this album. I think it's just bad. I count 5 tracks that I really do not care about, which is more than half the album. Aces High and 2 Minutes are nice, but they aren't the very best amongst the Maiden's classics either.
The album gets saved by The Rime Of The Ancient Mariner which is an absolutely great song, and is the sole reason it beats the next album on the list
13. No Prayer for The Dying
The title track is amazing. Mother Russia is amazing. I love those two song. The rest of the record isn't good. I might be in the mood for something like the Assassin once every 3 years, but really, I wouldn't shed a tear if the other 8 tracks were wiped off the face of the planet.
14-17. The rest
Sorry, but non-Bruce Maiden is just not for me, I've tried to listen to it and I just don't like it.