I'm not sure which play I like better

Villian and I have been going back and forth for quite some time. His range of hands here is pretty big, I am next to 100% sure that I am ahead right now. I am having some trouble deciding if it is better to 3bet the flop or to donk bet any non-heart turn.

What do you guys think?

Party Poker 0.50/1.00 Hold'em <font color="#0000FF">(5 handed)</font> link

Preflop: Hero is BB with 6[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/club.gif[/img].
UTG checks, <font color="#666666">1 folds</font>, SB completes, Hero checks.

Flop: (3.00 SB) 5[img]/images/graemlins/heart.gif[/img], 6[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, <font color="#CC3333">UTG raises</font>, SB folds, Hero...