recently "found" a hot-chilli-ketchup......... yum-scrum...... failing that 'brown-sauce' or the somtimes a bit too fruity 'hp' has to be my fave's.... dunno if you can get these outside the UK though
You use some of the above sauces to make other sauces like salsa for example.(Tabasco Sauce, Worcestershire Sauce et al.) Being a cook I use all the above listed sauces fairly regular. Anyone who knows anything about cooking knows that "the secret is in the sauce" in like 90%+ of cooking. I think it is best to know to make and have as large a variety of sauces on hand for cooking. I can't really say which sauce is the best only that I hate Ketchup and BBQ sauce is not far behind.
EDIT: One thing I know people like is sugar.(people like salt too.) But even that doesn't tell me what sort of sauce is the best. Everyone likes sugar but that doesn't mean everyone likes the sauce with the most sugar. IMO the most ingenious sauce listed above is tabasco sauce. Not because it tastes great on its own but that it is called for in so many recipies. Then again so are worcestershire sauce and soya... So in my bias opinion I would go with tobasco. Tobasco gets my vote.
Vote for soy sauce, not the best tasting one, but I don't know if I can live without it. Soy sauce + wasabi, is generally the combination, but there are other combination too. A very versatile sauce.