Not strictly a fastfood place, but Greggs is getting my vote anyway :tastysausageroll:
And my local chippy does a killer Kebab (I think you Americans call it a Kebob, is that right?)
We call it a Shish Kabob or Kabob for short.
I can't vote for any of those fast food chains as I hate them all, but since everyone else seems to be mentioning places that aren't worldwide (I've never heard of Greggs) I'll put my vote in for a Greek place called "Greek Delights" and secondly a bizarre, tiny burger joint called "White Mana".