Cool, another one of these! I assume this is personal opinion and not objective, so...
10. Amputated
"Slam Pig"
I don't know if many know this or not, but one genre I keep getting drawn into is "slamming brutal death metal", where the vocals sound like dying frogs, the blast beats are off the walls, and the riffs are fat and ugly. It's a very underground subgenre but it's a lot of fun if you can get into it. Beyond all the others, Amputated is my favorite band in it and their album Wading Through Rancid Offal is one of my favorites... period. The opening track, "Slam Pig", is easily one of the best death metal songs overall. It's got a lot of fat, juicy riffing, a vocalist that is so indiscernible that no lyrics to it have ever surfaced online, a drummer who knows his stuff, and a lot of good bass that keeps things in line. Add in the spoken word intro that begins the song, and you've got a three-minute monster that only some people - like myself - can enjoy. But what a monster it is.
9. Slayer
"Raining Blood"
Talk about a metal song where every just comes together to deliver a brutal crack over the head in music form. From the thunderclap and rain that open the song straight into that incredible riff that plunges us into darkness, despair, heaviness, brutality - this is a tour-de-force of thrash metal. The lyrics are evil, the riffing is monstrous, the solos are wanky, and as a whole, it just stands up very well against any of its peers. Fucking great stuff.
8. Mercyful Fate
"The Oath"
As far as the whole "metal is Satanic" thing goes, Mercyful Fate were the kings of doing everything to make religious people feel uncomfortable. "The Oath" has lyrics that are pretty much a black mess recitation sung is high-as-fuck falsettos over some of the best dual guitar in metal. Shermann / Denner are a pair unlike any other, and they make the music have a nice orange tint to it. King Diamond is, of course, a metal god, and this song is his crowning achievement as a singer. From the opening synth bit to the end of the song, "The Oath" is a metal masterpiece.
7. Ahab
"Old Thunder"
Ah, funeral doom, another inaccessible genre for a lot of people. The slow pace can often deter listeners and thus it takes a special kind of band to open up the genre for others. For a lot of people, including me, Ahab is that band. "Old Thunder" is a great song to introduce people to the genre, with a nice soft opening guitar bit that leads into a thunderous riff piece and some great growls from vocalist / guitarist Daniel Droste, this song never lets up. Nearly ten minutes long and every single movement is monstrously epic. And don't forget Cornelius Althammer's thunderous drumming! Reminiscent of the ocean and one of the best songs on The Call of the Wretched Sea, this is a doom metal classic.
6. Death
"Crystal Mountain"
Death's 1995 classic Symbolic was really breaking away at the confines of the death metal genre, with Chuck Schuldiner utilizing a lot of different pieces to make it feel different, including a different singing style from his usual growl. He's still growling, but it's a higher pitch now and it works really well. "Crystal Mountain" is the undoubtable highlight, with a great riff, some soft elements, a great solo - as a whole, it's just really fucking awesome. Easily the band's finest moment together and some of their most poignant lyrics.
5. Judas Priest
"Hell Patrol"
For many, "Painkiller" would be the go-to Priest choice, but "Hell Patrol" is my favorite from them and a really great metal song overall. A thunderous intro announces its entry and then moves right into a great riff that backs the verse. Halford's voice sounds amazing, both in the lower and the higher notes. The chorus is simple but effective, the bridge and solos are great. The final verse-chorus is a monster, and as a whole, this is a fiery track from a fiery album. Love it.
4. Sabaton
"Ghost Division"
I mean... what's more metal than a song about tanks? A quick drumbeat explodes into one of Sabaton's best riffs (and utilizes some great synths too) and Joakim Broden showcase how effectively he can use his voice which, admittedly, isn't one of the best as far as singing goes, but is the only thing that would fit this song. What a song, too. Based on Erwin Rommel's 7th Panzer Division, this one has a lot of bite and power to it and a really great chorus. Power metal / war metal classic.
3. Alestorm
"1741 (The Battle of Cartagena)"
Speaking of history-inspired songs, Alestorm seemed to take a page out of Sabaton's book for Sunset on the Golden Age, when they wrote "1741 (The Battle of Cartagena)". It's a song about the English fleet on course to annihilate the Spaniards during the War of Jenkins' Ear and by god what a song it is. The 8-bit opening moves into a great keyboard riff backed by fiery guitars. Bowes's standard raspy voice fits perfectly here, and the lyrics are some of the band's best as well. It's a seven-minute masterpiece and I goddamn love it. One of the best songs ever.
2. Bruce Dickinson
"Chemical Wedding"
Speaking of the best songs ever, Bruce Dickinson himself wrote several of them for his album The Chemical Wedding. Featuring Adrian Smith and Roy Z with a lot of deepness, heaviness, and bite in their axes, and some of Bruce's best vocal moments overall, it's a masterpiece album, and the one song that stands out from the rest is none other than the title track. If this had been done by any other group of musicians, it would have just been another song - instead, here, it's a fucking masterpiece. Great lyrics and a great verse are only the beginning - the chorus is the best part of the song, with arguably Bruce's best performance and it's hard not to cry from the sheer emotion of it all. Fucking phenomenal piece of music.
1. Iron Maiden
"Rime of the Ancient Mariner"
As good as many other songs are, the definitive metal song, in my mind, is Maiden's 13-minute epic from the Powerslave album. There were long songs before "Rime", and there were long songs after it, but none defined the "metal epic" half so well as Maiden did with it. Every moment is fantastic, from the first verses to the quiet piece to the instrumental section to the very end. Literature has never been so accessible. Metal has never sounded so good. "Rime of the Ancient Mariner" is a song written by the gods. There's no other metal song that deserves the title as much as it does. Masterpiece.