I prefer BetterTouchTool - its more flexible. However, I have found that if you have too many gestures at one time - there's more likely hood of a couple gestures being activated unexpectedly ( i.e., bugs ).
I haven't tried bettertouchtool, but I can vouch for Magic Prefs, it works really well.. I've also tried MouseWizard which isn't free and its horrible.. doesn't work very well