I've tried a few out. Some of them seemed slightly better than the DC pad in a minor respect, but the main DC pad wins out for me for all around quality.
-Madcatz pad - had a very good joystick, but the dpad was mushy and terrible and the buttons were kind of mushy
-astropad - I disliked how the joystick could "spin" on it (maybe it was just my friend's that was broken?), the design was also comically bulky but maybe that makes it cool in retrospect
-quantum fighterpad - I didn't care for the bulky design and the triggers seemed rather odd shaped and like your fingers could slip off of them when trying to press them in without making them register the input