KKs

Really hard choice.
OTT, if you're behind to a straight there's no way to catch up.
If behind to a set, you have two outs.
You block only the heart draw.

If you're ahead, you're ahead to draws nothing has really changed since the flop.

On such a board, would not betting the flop be the better idea?
Overcards and draws will call, but nothing better will fold

Personally I'm inclined to fold this turn -- but then I'm 🐔chicken

It is the perfect bluff spot, so that also means that it is the perfect spot for opponent to get value from overpairs etc

turn or I check or I bet 1/3 pot, you hasn't 3 and many set, as played call and check push on ♥ river