First I used the Saitek P-660, which was great for fighting games due to the 6 face buttons. But the internal wiring is flimsy so the controller gives out within a year. I went through 2 of them.

Then I used a Logitech controller which looks like a smaller PSX controller. They are flimsy as well. My first one fell a foot and a half and landed on the heater, and the d-pad broke off. So I got a second one and that one lasted until late last year. It technically still works, but when you push right on the d-pad it feels strange, like the pad will just snap off.

Now I use this product from Komodo where you can plug two PSX controllers in. It works but just barely, due to the fact it keeps shutting off. You'll be playing and all of a sudden, the controller stops working, so you have to unplug it then plug it back in.

I also use my wired PS3 Gamestop controller. It sucks for fighters but is good for everything else.