I eat them many ways.
When I eat them with a steak and some salade I enjoy them with some mayo and ketchup. Sometimes even cocktail sause or I just mix the mayo and ketchup, it is almost the same. Sometime I put some gravy from the meat on the fries, not to much because I hate soggy fries (there is only one exception)
I also like to eat them with Mussels and I just put some salt on them. No sause, it doesn't work with teh Mussels.
When I go to a Friterie, baraque à frites or however it is called in English (we just call it a frituur) I like them a lot with some meat spices and some mayo or Diablo sause.
They are also very good with some roasted chicken (a whole chicken!) Just some appel mouse and some salt. I get hungry just thinking about it.
Now the best way to eat them is with Beef stew (http://www.globalgourmet.com/destinations/belgium/stew.html#axzz2WzUuyag0) Just put the fries on your plate and put the stew on top of it. Make sure you have a lot of sause. It is also a good idea to get someone without tastebuts near you so they can pull you away from the table when you start eating your plate. Trust me you will want to do that. Oh and drink a glass of good Belgian beer with it. And I mean a good beer, not some dishwater beer.
But this is all assuming you eat Belgian fries. I hate french fries, the French don't know how to make good fries. They always use the wrong kind of oil or fat. And they often use it to long and bake their fries to long. I'm soory if any Frenchmen find this offensive but I have been in France enough to know that it is true. We Belgians make the best Fries. The Duch (from Netherlands) also know how to make decent fries, but they learned that from us)