Best app to assign custom mouse buttons?

[yalag]

I know there are quite a few apps out there that can do this, but which one is the best for mapping the extra mouse buttons to do custom actions for a specific app. I want app specific use for these extra buttons. I think I have 4 extra buttons on my mouse. Thanks

 

[Tomorrow]

I used to use Logitech's software with my Logitech mouse, it works pretty well for that.

These days I use BetterTouchTool, but as far as I'm aware that's only for touch pads.