I love fries, or as I grew up in Toronto calling them, chips...with mayo, with malt vinegar, and/or gravy...but...NO ketchup, please.
And that's only if the fries/chips in question are the thick "English style," chips, made from fresh potatoes. Ketchup does not work with those. Save it for replicachips, like McDonald's.
If said fries/chips are the skinny French style we call "frites," then we limit the toppings to the vinegar, and maybe the mayo.
And, if we're feeling really low-down Canadian, and ready to salute our French cousins, we love a Poutine--that would be yer thick chips with tons o' gravy [or what's called Swiss Chalet sauce here, or St-Hubert sauce--those are broiled chicken chains that make a good greasy chicken sauce with mysterious seasonings...]and cheese curds on top.
Yup, a poutine is disgusting. But quite good.