Trick question. American.
A true purists cheesesteak is steak, american cheese, and fried onions on an amoroso roll. Whiz is for fucking tourists, we tell them to go to Pats or Genos so they don't fuck up our normal spots. Every few months, some young photogenic white person, usually from some "foodie channel" like Bon Appetit or Tasty, will make a TOP 10 PHILLY CHEESESTEAKS video and they will have a list of mostly tourist traps and a few legit joints. Then out of those few legit joints, some get ruined by the massive influx of tourists and fame and their quality goes down as output goes up. That's why you never tell anyone where you favorite cheesesteak is from otherwise it will get ruined.