Here is the list of Marvel Heroes who has the potential to become prominent with great storytelling and plot convience.
1. Nova (Richard Rider)
2. Wasp (Janet Van Dyne)
3. Doctor Voodoo
4. Mockingbird
5. Wonder Man
6. Iron Fist
7. Hank Pym
8. Thunderbolts
9. Champions
10. Blue Marvel
So far, all I can say is that they're underrated and neither being used much in Marvel these days. Hopeful everyone could express their opinions which Marvel characters you wish to see more of them.