Usually most arcades use Ultimates, you can tell by the more shiny stick. If it was a new super joystick, it'd have ridges, and if it was a competition, the corners would be VERY easy to tell. I think the Tekken 4 machines use competitions though, and the CvS2 and other capcom machines use Ultimates. I know for sure they don't use 49-ways because those are for games that require that type of detection, and I don't know of one arcade machine that comes stock with perfect 360s. Once I played a MvC2 machine that had a comptition joystick in it, and the super-moves were hellza hard to do after air combos.
-Conclusion: Namco games usually use Competitions, Capcom games usually use Ultimates. I wish they'd use Supers though, cause I've played a few capcom machines that had their joysticks changed to supers, felt helllla good.
-CthulhuLuke