8bitdo M30 controller
The 8bitdo M30 is the controller I use for fighting games and playing sega stuff on retroarch. It's probably my favorite controller. The D-pad is the nicest I've ever used, especially for doing fighting game specials, and I find the 6-button sega layout more comfortable than the common 4-button layout, although a lot of games are designed around the 4-button layout, which makes it a little annoying to use. I would certainly recommend it to anybody looking for a controller for fighting games/sega stuff.
The D-pad is nice, but can feel mushy when you're trying to press specific directions. It probably has less precision for that kind of gameplay than a standard design, but it's more than precise enough for me in fighting games and everything else I play with it.