100NL,TPTK facing resistance

villian is 18/11/1.8 with river AF of 7 and 3.7% 3 bet over 250 hands. B/f, c/c or c/f ? I notice that there are lots of missed draws in his range as well as slow played sets & TPGK.
No-Limit Hold'em, $1.00 BB (7 handed) - Hold'em Manager Converter Tool from FlopTurnRiver.com

Hero (MP2) ($126.70)
CO ($155.55)
Button ($226.45)
SB ($198)
BB ($98.65)
UTG ($128.90)
MP1 ($101.50)

Preflop: Hero is MP2 with Khttp://www.flopturnriver.com/phpBB2/...iles/spade.gif, Ahttp://www.flopturnriver.com/phpBB2/...miles/club.gif
2 folds, Hero bets $4, CO calls $4, 1 fold, SB calls $3.50, 1 fold

Flop: ($13) 6http://www.flopturnriver.com/phpBB2/...es/diamond.gif, 9http://www.flopturnriver.com/phpBB2/...es/diamond.gif, Khttp://www.flopturnriver.com/phpBB2/...miles/club.gif (3 players)
SB checks, Hero bets $9, CO calls $9, 1 fold

Turn: ($31) 4http://www.flopturnriver.com/phpBB2/...iles/spade.gif (2 players)
Hero bets $20, CO calls $20

River: ($71) 2http://www.flopturnriver.com/phpBB2/...iles/heart.gif (2 players)
Hero ?

against someone with higher agg factor i check and dont fold - here id probably bet as a 1.8 agg wont bluff at this river too much IMO with draws

he has a set less often cos board flopped two tone. Still has it sometimes, but also KQ and draws. I prefer bet-fold to check-call cos he's rarely raising as a bluff but also only rarely bluffing when checked to - yet will call some spaz hands. Don't make it too obvious that you're blocking though