Villain is 30/15 over 30 hands

Full Tilt No-Limit Hold'em, $0.02 BB (6 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

BB ($2.15)
UTG ($2.49)
MP ($2.46)
CO ($3.94)
Hero (Button) ($2.03)
SB ($1.76)

Preflop: Hero is Button with K, A
UTG calls $0.02, 1 fold, CO calls $0.02, Hero bets $0.10, 3 folds, CO calls $0.08

Flop: ($0.25) 10, J, Q (2 players)
CO checks, Hero bets $0.20, CO calls $0.20

Turn: ($0.65) J (2 players)
CO checks, Hero bets $0.40, CO calls $0.40

River: ($1.45) A (2 players)
CO checks, Hero ?

I think theres lots of Qx and Jx in his range so checking misses a lot of value. At first I want to b/f. But then what if he raises with a king? Lots of kings in his range. I don't feel good about bet/call since i'm not sure about this opponent's tendencies. So go for value, or protect the stack?