User blog comment:NintenFox974/Controller Questions?/@comment-24796436-20140918023406

In my opinion, you can't really go wrong as long it works without any malfunctions soon after purchase. In other words, steer away from cheap looking off-brand controllers unless you don't mind shelling out on a replacement.

Practically any store with an electronics or PC gaming section will have a USB or even wireless controller. Most of those work just fine. Just make sure you configure the inputs to something that works for you and seek out a favorable and/or familiar (physical) button layout. That's all there is to it.

If you have any PS1/PS2 controllers laying around, I recommend the USB adapter for them. If you can't find it in stores, try Amazon or some other online retailer.