Typically, the M30 by 8BitDo. It's the most like the Sega Arcade Pad and the Sega Saturn controller that I used to use back in the 1990s. I have a TON of game controllers and thus a ton of options for playing games, but that's what I use the most. If I'm feeling especially fancy, I'll break out a joystick like my MadCatz Street Fighter IV stick (modified with hair-trigger Sanwa buttons), a modified Hori PS fighting stick, or the ridiculously small Street Fighter II Champ joystick released by Numskull. (I think it was Numskull. I don't really remember, honestly.)