#2 EC3

In the cases of Apollo Crews and Nia Jax, it was evident that they were called up before they were ready. That wasn't the case with EC3. Even if he was called up immediately after signing for WWE, it wouldn't be surprising as he has all the tools to be a big superstar.
His strength lies on the mic but he's never allowed to speak. Even Jon Moxley revealed that the reason the company neglected him is that EC3 and himself were working Live Event matches and EC3 was supposed to be the babyface.
Due to no fault of his own, EC3 was booed and this angered the office, leading to them treating him the way they are now. EC3 is an extremely skilled Superstar and would be perfect for a platform like NXT. Even though he has always been "main roster ready", his success in WWE will most probably be limited to NXT.
He could finally become a title challenger again and have a big career rejuvenation.
Also read: 5 things Vince McMahon shouldn't do at the WWE draft but probably will anyway
Becky Lynch has been challenged HERE.