Depends on the quality of the hot dog and the location.
Outside, hot dog stand, middling quality? I’m putting on everything they’ve got. Ketchup, all the mustards and relishes, pickled everything, sauerkraut, shredded cheese, olives, chopped onions, fried onions.
Outside, best quality grilled hot dog? straight up – no bun. I’ll put some ketchup and coarse mustard on my paper plate and dip my dogs in it.
Inside, Harvey’s? hot peppers, chopped tomatoes and lettuce, Harvey’s dills on top and on the side, mayo. Sort of a side salad balanced on a dog.
Inside, fancyish restaurant that does dogs? Chunky mustards and garlic mayo.
Outside, at a steamer truck? mustard on a squishy bun.
At home? I’m slicing my dog along the top and putting shredded cheese in the slit – then mustard, ketchup and relish on top.