I recall reading on the subject before and it was mentioned that it’s usually ls32/ls56. I’ve also read that the game was first released on the capcom impress cabs which used an ls 56 with an octo gate. I suppose I’ll be over there soon enough and find out for my self, does anyone which is most commonly used, then and now…?
Capcom Impress was released after SF2 (all versions but Hyper).
Several accounts from people who went to Japan report LS-32 as the joystick used for SF2. Damdai stated they have Sanwa buttons, but I don’t know if they replaced the original buttons with those or they were stock.