Powerslave - a definition of epic, timeless art!
Killers - the classic image of Eddie and background, enough said.
Brave New World - the art is very captivating with the futuristic city and (even with just) Eddie's head. The colors add a lot, striking image.
Fear Of The Dark - one of the best idea for Eddies, doesn't even need a background, it's that strong.
Somewhere In Time - the details are special and create a whole world, you can't beat that. That's always important.
Virtual XI - underrated idea, one of the best covers since the 80s in this regard. The details could have been better/better drawn, but it captures your imagination, which is always good. Good mix of colors too.
hm: A Real Live One (cool Eddie imo), Death On The Road (if it wasn't for its background) - and I definitely would have voted for Book Of Souls & Senjutsu if it were their booklet arts, despite being very strong Eddies.
It will be harder with singles.