I personally like my hambergers and hotdogs au naturel, AKA: No toppings. ^_^

Personally, I don't like hotdogs with just ketchup or mustard on them, but if there's nothing else, I'll either put both or just mustard. So I guess my vote is mustard.

I usually put diced tomatoes, diced onions and relish on my hotdogs though, with mayonnaise on the bun.

I never put anything else than ketchup on a hot dog. Actually, I never don't put a ketchup on a hot dog.
I also hate mustard, even through the last time I tasted it was when I was a child.

Most definately ketchup! I hate mustard. Infact, I hate it so much that I cannot even stand the smell of it! Bleck!

I also hate relish. I think it is very disgusting...Just keep things simple! Just one squirt of ketchup is good enough!

I put both on mine.

Well I don't like mustard at all, so this is a very easy decision, I vote ketchup.