The Torch was supposed to be the star of Fantastic Four, according to early interviews with Stan. It took a while for Marvel to figure out that Ben was going to be the character readers identified with. So in that sense, the Human Torch has been a disappointment for them since his revival. He's popular enough, but not a star as they'd hoped he would be.

As for Namor, I'd argue that he was very successful for about ten years or thereabouts, from the beginning of his run in Astonish to the mid-'70s, when his own title started to decline. His sales in the early direct market were comparable to Cap's or Iron Man's, slightly below Thor and The Hulk, and a little better than Daredevil's. About average for the second tier of books in the early and mid-70s.
Who am us, anyway?
--The Firesign Theater