This might be an unpopular opinion, but as a bass guitarist/musician Steve Harris > Geddy Lee (or at least his equal).
-Writes the songs, and they are complex, classically-influenced 6+ minute songs at that.
-Incredible bass playing speed and chops. His galloping right hand technique is legendary. He doesn't stay pedaling the root. If you listen to a live show where the bass cuts through well, he is basically playing a unison riff or counterpoint riff to the guitars throughout the entire song. With his fingers.
-When his signature "West Ham United" bass was released by Fender, I remember seeing a youtube video of a jazz snob doing an instrument review and basically looking at the camera and saying, "Look, I know what you are thinking...Iron Maiden? But in doing research on how this bass guitar came to be, I found myself humbled and inspired by Steve Harris' musicianship."