One of the best sounding Maiden albums in my opinion is Killers. The atmosphere in that record is very unique and special to me.
Killers has a world-class production for obvious reasons. They had just gotten a legendary producer and he was willing to show what's in him. However, I prefer the way the debut sounds because the rough, dirty edge serves Paul much more than an excellent production that shows us how limited he is and how much the band has outgrown him.