For what it's worth - and purely from anecdotal evidence (read: friends and discussion groups) - growing up in Europe there was this impression that Powerslave was much more loved in the US than elsewhere. I mean, of course it's generally considered "classic" Maiden everywhere (with plenty of "classic" songs in it to back this up), but the feeling was this is the album that made Maiden huge in North America, so perhaps there's special appreciation correlated with that? Where I was, The Number of the Beast and Piece of Mind would instead almost invariably rank higher whenever I asked...
Can you guys confirm this? Do I even have the "facts" right? (meaning: Powerslave was the album that truly broke Maiden big in the US?)
I think the album that "broke" Iron Maiden in the US was The Number Of The Beast. They were in heavy rotation on MTV with Run To The Hills. They had a great opening slot on Judas Priest's Screaming For Vengeance tour, another album that was huge.
Their first headline tour was with Piece Of Mind. The singles did pretty well, Flight Of Icarus first and then The Trooper. In 1983-1985, heavy metal/hard rock really started to become mainstream, and by that, these bands did well enough to support arena tours.
Powerslave featured the lead single Two Minutes To Midnight, which had decent rotation on MTV. They toured everywhere in the US. With their Eddie logo, and MTV support (don't believe any bullshit Bruce Dickinson tells you) the kids flocked to them. While Maiden didn't have radio support, MTV played them a ton.
In my opinion, it was the Live After Death album and video that was way more impactful than the Powerslave album. They were really the first of the hard rock/heavy metal bands of that era to do the "double live" album, the likes of which were so popular in the 70's. The video was shown on MTV, and I think that was the thing that really catapulted them. But again, bands like this were extremely popular, to the point where in another year or so, rock, with Bon Jovi, Motley Crue, Def Leppard ruled the charts.