#2 Samoa Joe
Samoa Joe is inevitably main roster bound, or at least he should be. Joe is a proven veteran and was one long before his time in NXT. He's done outstanding since arriving in NXT, and there's simply nothing left to prove.
Joe challenged Nakamura at Takeover for the NXT Title and won, but in a perfect world, Joe would have lost the match and would have discretely headed to Toronto on Monday for a Raw debut. But that's not happening anymore at this point.
Samoa Joe is still the perfect candidate for a jump to the main roster. He's certainly proved himself to be capable of doing things the "WWE way," now it's just time for them to give him a shot.
Joe and Zayn have faced each other in some stellar NXT matches. It only makes sense to revive this feud on the big stage.