I tried both. Pad was more comfortable for me, since I grew up with a controller in my hand.

Fightsticks: * expensive. EXPENSIVE. $$$$$$$ * easier for certain inputs. For some things you'll have to use special bindings on a pad. It's not that big a deal, but the edge goes to fightstick. * playing in-person, your opponent can listen for your button inputs. * big and heavy; inconvenient. Do you attend events? You'll have to lug that thing around. * the components on a quality stick will last you a while. But if you play on console, you'll need to upgrade the PCB to support later consoles as they're released.

Pads/controllers: * less expensive. But they also wear out faster, which is the next point. * wears out faster. The button membrane wears out faster than the parts on your fightsticks. If it happens, buy a new membrane for $3 on ebay and you can replace it yourself. If you know how to use a screwdriver, you can repair a broken membrane. But it is extra work. * some inputs are harder. For example, simultaneous inputs involving both trigger buttons. * compact and convenient. * quiet. Play at night all you want and nobody cares. * to keep up with new consoles, you need to buy new controllers.

AFAIK most pros use fightsticks, but it doesn't really matter that much what you use. Plenty of people play with their keyboards just fine. brolylegs is a #1 Chun Li who uses three fingers and his mouth.