Neville is a beast but by no means does he have better charisma. If he did, he would be more over than Balor but he's not and has never been (and likely will never be, as a babyface).
They both had runs as NXT champion... Balor got superstar reactions, Nevile got respectful lukewarm pops. Babyface Neville didn't come across as a star at all. Heel Neville can absolutely reach main event status though. He's establishing himself as a killer in the CW division. That's the perfect way to build him as a threat in the heavyweight division. Does anyone not see Neville as a more credible threat in the HW ranks than before his CW run? His booking is working perfectly.
Balor is Reigns Jr in the sense that that a majority of the women in attendance apparently get wet over him, the difference being that the type of fans who boo Reigns generally fukk with Finn because he has Japan cred or whatever. Why wouldn't "Reigns Jr without the boos" get a mega push?