#1 The Undisputed Era

As a group, The Undisputed Era are fantastic, but with the likes of SaNity not getting much screen time on SmackDown Live right now, the best thing for this group is to keep them away from the main roster.
The quartet consisting of Bobby Fish, Kyle O'Reilly, Roderick Strong and Adam Cole made their goal for 2019 known: to hold all the gold in NXT, and that's off to a rocky start, but it's safe to say that NXT in 2019 is going to heavily revolve around them.
Cody Rhodes' uncle is a WWE Hall of Famer. More details HERE.
In terms of in-ring talent, there has rarely been a group in WWE history as good as this one, but the WWE is already stacked with such talents, so it makes sense to keep them in NXT for longer.
Hopefully, though, the WWE doesn't add or take members away from this group, because, in 2020 or 2021, they will be ready to take over the main roster the exact same way they did NXT.