My $0.02
I basically stopped after 1992 when Bruce split. I have heard some latter pieces I liked but can't critique past that point, which hamstrings my assessment.
Iron Maiden has to be in the top 3. I am a Paul fan though his power/range is nothing like Bruce's... different animals though, and the feel of this album is a seedy, dangerous one that Bruce can never touch. More importantly, EVERY song has merit and strength. One of the biggest shortcomings of the band is that they can produce an an unbelievable riff then spin it 90 degrees to some ill-fitting poppish melody, or worse, they can produce an album with 4-5 classics/anthems and a similar number of irrelevant cutting room b-sides (somewhere in time comes to mind).
Powerslave has to be another top 3. This is the one where Bruce found his groove with the band and the power and maturity peaked for them (at least during their most influential era). It has its share of filler like Back in the Village and (perhaps Lossfer Words) but these anthems are among their best work, including Aces, 2 minutes, and Rime. Even the "solid-middle" tunes like Flash and Powerslave destroy the best offerings on many of their other albums.
Number of the Beast is simply a classic. Probably the 3rd of the top 3... a seemless transition from the gritty punkish rock of the Paul D era to the melodic metal that defined thier sound ever after. So many great anthems and classics on this.
Killers, Seventh, Piece, and Stranger are all great, but known for the inconsistent classic track/irrelevant track Maiden is famous for. Prayer is absolute crap as far as maiden-caliber music is concerned. This was the album that nearly caused me to quit Maiden.
FotD was the album that redeemed them... amazing melodic guitar work, powerful vocals and listenable songs... definitely a top 5.