Obviously, these things are subjective...
Every Iron Maiden Song Ranked From Worst to Best | Loudwire
The top 20:
20. "The Wicker Man" - 'Brave New World' (2000)
19. "Prowler" - 'Iron Maiden' (1980)
18. "Paschendale" - 'Dance of Death' (2003)
17. "Aces High" - 'Powerslave' (1984)
16. "Fear of the Dark" - 'Fear of the Dark' (1992)
15. "2 Minutes to Midnight" - 'Powerslave' (1984)
14. "Murders in the Rue Morgue" - 'Killers' (1981)
13. "If Eternity Should Fail" - 'The Book of Souls' (2015)
12. "Remember Tomorrow" - 'Iron Maiden' (1980)
11. "The Ides of March" / "Wrathchild" - 'Killers' (1981)
10. "Iron Maiden" - 'Iron Maiden' (1980)
9. "Seventh Son of a Seventh Son" - 'Seventh Son of a Seventh Son' (1988)
8. "The Trooper" - 'Piece of Mind' (1983)
7. "Children of the Damned" - 'The Number of the Beast' (1982)
6. "Powerslave" - 'Powerslave' (1984)
5. "Phantom of the Opera" - 'Iron Maiden' (1980)
4. "Killers" - 'Killers' (1981)
3. "Rime of the Ancient Mariner" - 'Powerslave' (1984)
2. "The Number of the Beast" - 'The Number of the Beast' (1982)
1. "Hallowed Be Thy Name" - 'The Number of the Beast' (1982)