villain is a 21/15/6/48 (vpip/pfr/3b/ft3b) reg with a 4bet of 10%, call 3bet of 43% and EP first in raise of 13%. I dont see him as a good regualar since he never puts me in tough spots and I saw him making some very questionable (mainly river) calls.

Some FR regs would flat KK in this positions but given his high 3bet calling % and his reasonable wide opening range, I think the 3bet is the only option. Note that there is a huge whale in the BB with a vpip of 92(3bet 8%). Fishes behind me obv. change my plan in some spots to just flat rather than 3betting standard but in this case, I pretty much see him calling almost the same range to my 3bet as to the normal openraise. It might affect villains opening range tho, but I dont know if he actually raises looser with the fish in the BB.

Anyway, the fish folds and the reg calls, so we are HU. His opening range should be sth like:

22+ ATs+, AJo+, KTs+, KJo+, QTs+, QJo+, JTs wich is 14,3%

I dont see him calling 43% of that hands to my 3bet here given the positions but I still assume he is calling a very wide range:

66-QQ, AQo, AJs-AQs, KJs+, QJs

My first thought during the hand was, that this board hits his calling range pretty hard. So I decided to check behind as I did not see 3 streets value agains a worse hand and I might isolate my self agains better hands. Furthermore, this would def. be a flop I would give up my 3bet bluffs on. I did underestimate the amount of worse pairs he can have he when I was playing, so I think a bet would be good too. I think if I bet he will fold all his pairs of TT- and call everything else(all of that hit the flop). Still have 60% agains that callingrange.
Anyway I stick with the fact, that I wont get 3 streets agains one pair hands + excellend spot to balance my give ups. What do you think? I still pref. the checkbehind.

following plan

following plan