I use the windows media player classic from the CCCP. You'd hope that this program plays all anime fansubs equally good, at least I thought that is what it was arranged for. In the two last Yibis eps I had massive lags in the openings and in 543 small ones after the advertisement break, in 544 also massive ones in the action sequence in which Kizaru lasers Arlong. Otherwise the eps where fine. It's strange how it lags at specific points. I don't personally think that action sequences like in the opening should demand that much more computing power like the lags seem to suggest, when the characters interact slower the framerate should be still the same and there is still sound. Whatever.
I might try some of the other programs, but it's probably less of a hussle to just take Horrible subs or CSS (btw both out now for 545)