I love it when WildRanger bumps his own year + old thread to add some comment that responds to nothing in particular, and then people ignore the WildRanger bump and just continue responding to the original topic.
So I'll do the same: For me, it's Piece of Mind. The run from Where Eagles Dare to The Trooper is perhaps the best five-song run of 80s Maiden (the other top candidate would be The Evil That Men Do through Only the Good Die Young), and then the album also has To Tame a Land. SiT is also very strong, and probably comes in right behind PoM as my third-favorite 80s Maiden album (Seventh Son is my #1), but I think it's just below the level of PoM due to Heaven Can Wait and Deja Vu.