#1 Aleister Black
The Dutch Destroyer made his name known throughout the NXT Universe last year during WrestleMania weekend. Since then, he has been a destructive force down in Full Sail. He is a former NXT Champion, sported a lengthy undefeated streak before it was snapped by Johnny Gargano, and has gone undefeated in every TakeOver event he has partaken in.
That's seven matches, and he has won every single one. Aleister Black has shown a level of dominance seen by very few in NXT, and a man of his talents would be very much welcomed in the Royal Rumble event.
Whether he does so as NXT Champion remains to be seen, as he is surely due for a one-on-one rematch with the current champion, Tommaso Ciampa. Regardless of that though, his entrance in the Royal Rumble would be a memorable one. Just don't be surprised if he walks into that ring and makes everyone in it fade to black.