I actually started early with gamepads, dating all the way back to the Gravis and the original Logitech Wingman, but it might be relevant that I still primarily use a mouse and keyboard, and especially for anything that requires precise aiming.

I use a gamepad for emulated console games, since they're designed for a pad, and for things that require free and flowing movement, so respond well to a stick or a d-pad - racing games primarily, and many platformers and similar action games. But for things that combine separate movement and aiming - first person shooters and RPGs and the like - I just think a mouse and keyboard is better than dual sticks ever could be.