Wait for the turn?

[CourtesyFlush]

Normally I am not one for slowplaying in multiway pots on the flop, but this may be a very good spot to do it. Better is a fairly solid player, everyone else in the hand (besides me) is very loose/passive.

Party Poker 0.5/1 Hold'em (9 handed) converter

Preflop: Hero is Button with K[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/diamond.gif[/img].
UTG calls, UTG+1 calls, MP1 calls, MP2 calls, MP3 calls, CO calls, <font color="#CC3333">Hero raises</font>, <font color="#666666">2 folds</font>, UTG calls, UTG+1 calls, MP1 calls, MP2 calls, MP3 calls, CO calls.

Flop: (15.50 SB) K[img]/images/graemlins/club.gif[/img], 2[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(7 players)</font>
UTG checks, <font color="#CC3333">UTG+1 bets</font>, MP1 folds, MP2 calls, MP3 calls, CO calls, <font color="#CC3333">Hero raises</font>, UTG folds, UTG+1 calls, MP2 calls, MP3 calls, CO calls.

Turn: (12.75 BB) 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(5 players)</font>
UTG+1 checks, MP2 checks, MP3 checks, CO checks, <font color="#CC3333">Hero bets</font>, UTG+1 calls, MP2 calls, MP3 calls, CO folds.

River: (16.75 BB) 2[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
UTG+1 checks, MP2 checks, MP3 checks, <font color="#CC3333">Hero bets</font>, UTG+1 folds, MP2 folds, MP3 calls.

Final Pot: 18.75 BB

Whats the verdict? Raise the flop or wait until the turn?