I consider myself a potato enthusiast. I just had this discussion at work today and truly realized my addiction.
McD's: either plain, if driving or w/s&s sauce, if sitting
Wendys & BK: plain
my local pizza cafe: pepper w/ parm cheese and dipped in ranch
my local pizza cafe if eating bacon/cheese fries: mozz, cheddar, & parm cheese topped with bacon and dipped in bbq sauce
my local Irish pub: Guinness gravy (I could drink the stuff)
my local bbq joint: cheese sauce
anywhere else: Heinz ketchup, if not available, nekked w/salt & pepper
Around these parts, it's cream gravy heavy on the pepper.... with a side of chicken fried steak.
But, my favorite fries are the Pomme Frites at Cafe Orleans at Disneyland. It's the first thing I eat there every summer. They are fries covered in minced garlic, parmesan and parsley, served with remoulade sauce for dipping.
Malt vinegar and plenty of salt, except at Texas Roadhouse where I dip their fries in the BBQ sauce they use on the ribs. I rarely eat fast food fries, but when I do it's just salt.
On the rare occasions that I have them, lots of salt. I dip in ketchup or tartare sauce, depending on the meal. I prefer 'chunky' ones, like at UK Epcot, not from fast food places.