I have a thing for Thousand Island dressing on things. That or pickle relish. Or both ! lol
Mustard is my favorite.
I probably use more mayo than any other, so I'll have to say mayo.
I use mayonnaise and ketchup the most.
I'm going with horseradish and tabasco. I have a feeling many won't agree. But, I do like my food spicy.
Frank's red hot sauce , I put that shhhhhhhhstuff on everything :E
Hot sauce, however it depends on what kind. Debomb ground zero is my favorite.
Homemade hot sauce.