I think influence outweighs popularity in terms of importance
But Blondie and particularly Debbie Harry has had an incredible influence on women (and men) not so much musically but on what a woman could be, do and represent within rock and roll
Roxy Music is always put down in the US but they are after Bowie the most important UK act until the Sex Pistols and the most important influence on the early 80s New Romantic movement (Duran Duran etc)