My vote has to go to Steak n' Shake for sure.
Steak 'n Shake has the absolutely, nastiest, rottenest french fries I have ever eaten. I worked at a place in NC that served the same bunch of hard-as-a-rock, crunchy-assed, stale fries. They switched them to regular, people-food french fries and their sales doubled within a month. People were so happy not to have to eat those crappy, nasty things that they were ordering the fries by themselves. Just a plate of your new fabulous, wonderfully tasty french fries, please. Yes. Thank you.
Bojangles gets my vote, if you can find one (go to North Carolina). They use Lawry's seasoning salt on them. Mmmm, arteriosclerosis.
I'll give you a Hi-5 just for admitting you like them. They do make the best milkshakes.