In my opinion, I think that the best fry is straight out of the fryer, liberally applied with kosher salt. If you need to add anything else right away while it is still piping hot, then its not a premium fry. Of course, a little malt vinegar can go a long way with mediocre fries, and I wonder why more restaurants don't offer it. I can understand a few that are too proud/confused to recognise that their fries suck, but plenty places have blatantly horrible fries that need a little more kick than just Ketchup.
On another note, when I make the frozen kind at home, I occasionally like to throw a little Old Bay on them for a little kick.
Also, 5 Guys Burgers and Fries has probably the best chain fries around. I especially like their liberal portions which allows me to bring some home to freeze (they actually freeze pretty well).
Well, I love french fries, and would love to hear what others have to say on the topic ...