A big problem with the presentation at KTLA and KTTV, from my perspective, is that they overwork their people. Micah Ohlman and Cher Calvin are on air from 5-7:30, then from 10-11:30. Meanwhile at KABC, Marc Brown is on air for a total of an hour and a half, maybe two hours a day.
As for the political ... take a look at the social media presence of some of KTLA and KTTV's on-air talent. It's amazing they're able to repress their feelings on air as much as they do!
I do think some of the political leanings come from on high at Nexstar and Fox, although it is somewhat tempered given the left-leaning population.
KCAL/KCBS seems a little right leaning as well, but I think that's largely from having an appropriately adversarial relationship with the powers that be, which are, obviously, left leaning almost everywhere in LA County.