I use a Nintendo Switch Pro Controller. It does the job for all of the systems I have on Retroarch.
8BitDo SN30 Pro Wired. Shaped like a SNES controller, the buttons are nice, has a layout that plays nicely for most retro systems, has a modern amount of controls. If I were to go back in time, only thing I would change would be to get the SN30 Pro 2 for the handles instead.