Almost any gamepad will do, as long as it does have at least one analog stick. I'd advice you to stay away from strange clone gamepads that no one has ever heard of, since these pads tend to have problems with some emulators (I'm saying this based on what I've read in the past, don't take it as gospel). Mind you that you can't use it in nullDC, since the emulator doesn't have a controller plugin that supports gamepads.
Chankast should pick the gamepad as long as you've plugged in in your computer and you are using ElSemi's controller plugin.