1.5k deep with BTN,  BB is 80bb deep. BTN is 82/52 and playing pretty reckless, aggro and getting it in to just gamble. BB is 42/4 and just passive an cally pf. I'm in SB. BTN has 4b KKxx shallower, but hasn't 4b anything but AA lately

BTN pot opens, I 3b QJT9ss, BB calls, BTN calls. Flop is Jh 8h 5s with like 340 in the middle, BB has 690 and i'm 1.2ish deep with btn. BB is almost never stabbing when I check, however, BTN is happy to bet a majority of stuff, but will also jam over a bet with naked KKxx. 

Bet or ch to start? And what size?