I don't know about Ezekiel Jackson. They seem to want him as a face for right now, judging by all of his matches since returning from injury (house show and TV alike).
Options:
Ted DiBiase: Once DiBiase finishes his business with Goldust, seeking the United States Championship is a logical next step. His match with Bryan on Raw was one of his best bouts. It's clear that WWE still sees DiBiase as a priority, hence his run with Goldust (he's been working with him at a bevy of recent house shows) as Goldust is considered as one of the best vets in getting great work from younger guys. In feuding with Bryan, DiBiase can have a good midcard feud over the midcard championship--which is unto itself an elevation--and get better matches on his resume from working with Bryan. Win/win. He just needs to finish his feud with Goldust.
Ezekiel Jackson: Face or heel, it could work as an intriguing match-up. Problem is, both Bryan and Jackson are protected, and they both (for now) are faces. So the timing isn't right at all for them to mingle with each other.
David Otunga: Doubtful, but for a one-off it might be sort of interesting. WWE could run it as a way to see if Otunga has any prayer of a future in wrestling. If he can't have a watchable match with AmDrag, forget it.
Primo: Deserves to be elevated. I think he'd have some good matches with Bryan. But probably more of a Superstars main event...?
William Regal: Get into the backstory CM Punk hinted at on commentary and this could be an epic feud. Not to mention, I'd love to see the matches.
Alex Riley: The ol' "I'll get the job done, Master!" angle... But I don't see it at all, since they've made Riley look like a simpleton every time he breathes the same air as Bryan, playing Porky Pig to Bryan's Bugs Bunny.