Hot dog toppings...do tell. For me...chili, cheese and onion.

Chilli, cheese
Or 
BBQ sauce
Or Ketchup 

Bacon, cheese and Dijon (brown) mustard.

I don't eat them anymore, but back when I occasionally did, I added only mustard to the wiener and roll.  

It's been a long time since I've eaten one, but as a purist, mustard is the only thing I put on it.

I don't put anything on them. Shocking, I know.

Like some others have mentioned, when I did eat them, it was usually with just a bit of mustard or a bit of ketchup or a bit of both.
Or "naked," too, like Jane S mentioned (she didn't use that word, I did, ha).
All sound good.