I'd like to see Ghost Rider rebooted without the weird random villains that stole names from completely different comic book villains. Silver Surfer kind of got a bad shake too.
Doctor Strange is one of main ones missing right now, and a Cable story could be sort of interesting if it didn't devolve into generic action tripe. For random amusement, I want to see Beta Ray Bill in a Thor sequel
(there is a rumored X-force movie apparently, but it hasn't mentioned if its the Cable led 90s one or Wolverine's "Black Ops X-men" newer version, and the latter is obviously more cash-in value)
I could also get behind a Sentry movie, as odd as that may seem.