Lol all these answers are garbage so far. You do know Chael and to a lesser extent El Cucuy are intentionally doing their shtick for luls and promotion? It's straight-faced dry humor. I think the cringiest fighters are the ones that have a legitimate tryhard personality or take themselves way too seriously. For example:
Sean O'Malley - I like his fighting style and he's funny at times (I lol'd at his interviews about Andre) but boy is he fucking cringe. He tries so hard to be a "stoner" and be chill.
Mackenzie Dern - Her fake Brazilian thing is weird and cringe. I have no qualms about her embracing her heritage but faking the accent and mannerisms is a little much.
Ronda Rousey - Takes her self way too seriously and is way too tense about everything, one of those people that freaks out about the tiniest little tease to them.
Tito Ortiz - basically the same as Ronda but also even more cringe overly-serious trash talk. It's amusing seeing Chael giving so little effort to troll him.
Joanna (pre-rose) - Boogie woman was very cringe and it's always satisfying seeing a bully get humbled. Thankfully she calmed down a bit before the second fight, but afterwards she was clamoring on about how she won.
A lot of the TAM guys are really cringe with how overly serious they take themselves and their middle school trash talk. I mean, look at the name of the gym, Team Alpha Male, average height of their fighters is prob 5'7", compensation? I think so.
Travis Browne is pretty fucking cringe, I don't think there is any explanation needed, he's just a douche
Michael Johnson is kinda cringe with his trash talk
Schaub is cringe but it's cool because it's also funny how cringe he is
Mike Perry is borderline cringe but he's also kind of charming and redeemable in meme value