I've got 6 badges so far, so of those ones:
Cheren: Eh, boring.
Roxie: Kinda boring, although it does remind me of some bars I've been in haha.
Burgh: Fun, but I preferred his old gym.
Elesa: Kind of boring too, preferred her old gym (although I know you get to go in there too)
Clay: Fun puzzle, challenging enough, but not irritating. Probably my favourite so far.
Skyla: Fun, but a little irritating.
So yeah, Clay wins. Cheren probably loses, although I feel bad 'cause he's just starting out :P