Parmesan cheese to any pasta dish. Also like two specific chilli sauces. One is Lao Gan Ma Spicy Crisp Hot Sauce. Transforms any noodles or dumplings. Another one is this Russian style chilli and garlic sauce. IDK what it's called, all I know is the local Russian ethnic mini supermarket has it and it goes well with almost everything. Fried eggs on toast, Russian dumplings, noodles if I don't feel like having the other sauce, meat tastes a bit bland - throw this on it, transforms it. It's hotter than expected and has a good garlic taste.
Thousand island dressing. There's a reason people thought it was McDonald's secret sauce for years (and it's not entirely untrue tid is an ingredient in it) it's just that damn good. I restarted to get the low cal version of it unlike diet sodas or low sodium Soy sauces it doesn't taste much different.
As far as adding something to my meal goes, I don't mind adding some chopped up mushrooms and onions to a homemade burger. Also like using Worcestershire sauce to meat and whatever vegetables I cook sometimes.
McCormick's grilling seasoning - in particular the Montreal chicken and steak seasonings - are also really good.
Sriracha is surprisingly good on hot dogs (not one of those Sriracha stans that put it on everything) and basically any of the mexican hot sauces - cholula, valentina, tapatio, etc. I don't fuck with tabasco too much, the chipotle one is good but all the other flavors taste too much like vinegar to me.