These lists are usually always a waste of space, as it often compiles only the most popular of songs. For the heck of it, my list would look like this:
10 Paschendale- Iron Maiden (Dance Of Death, 2003)
9 Holy Wars... The Punishment Due- Megadeth (Rust In Peace, 1990)
8 Master Of Puppets- Metallica (Master Of Puppets, 1986)
7 Rainbow in the Dark- Dio (Holy Diver, 1983)
6 Creeping Death- Metallica (Ride The Lightning, 1984)
5 Peace Sells- Megadeth (Peace Sells... But Who's Buying? 1986)
4 Hallowed Be Thy Name- Iron Maiden (Number Of The Beast, 1982)
3 Tornado of Souls- Megadeth (Rust In Peace, 1990)
2 War Pigs- Black Sabbath (Paranoid, 1970)
1 Powerslave- Iron Maiden (Powerslave, 1984)
Now I bet there are few of you agreeing with this list. I doubt there's anyone who agrees that Powerslave is the greatest metal song of all time, but that is how I feel. No spot for Iron Man, because I prefer War Pigs. Some may disagree, but again it's personal preference (Iron Man is also an excellent song). Tornado of Souls IMO is easlily a top 10 song, yet never recieves the credit it deserves. And finally, I included Rainbow In The Dark despite many people preferring Holy Diver. So you see, personal preference count a lot in these lists. Am I saying everybody should accept these as the greatest 10 metal songs of all time? No. Am I saying that these are in MY opinion the greatest metal songs of all time? Yes. Heck, I could have made a top 100 and still there would have been a thousand deserving songs narrowly missing out
And if I were to do a top 20, then from 20-11 my list would look like this:
20 Iron Man- Black Sabbath (Paranoid, 1970)
19 Victim Of Changes- Judas Priest (Sad Wings of Destiny, 1976)
18 Call of Ktulu- Metallica (Ride The Lightning, 1984)
17 Stranger In A Strange Land- Iron Maiden (Somewhere In Time, 1987)
16 Battery- Metallica (Master Of Puppets, 1986)
15 Good Mourning Black Friday- Megadeth (Peace Sells... But Who's Buying?, 1986)
14 Crazy Train- Ozzy Ozbourne (Blizzard Of Ozz, 1980)
13 Raining Blood- Slayer (Reign In Blood, 1986)
12 The Trooper- Iron Maiden (Piece Of Mind, 1983)
11 Painkiller- Judas Priest (Painkiller, 1990)
Again this represents my own personal opinion- a mixture of 'popular' or 'obvious' choices and a few 'non obvious' songs from 'obvious bands'.