New Mexico hatch Green chilies on everything.

I do a chicken pizza using tzatziki as the base sauce instead of tomato. Initially I was going to have it on top, but decided to go nuts. With the other Mediterranean ingredients on it, goes deliciously.

A quarter-dash of cinnamon in anything that calls for ground or minced beef. Enhances the savory notes of the rest of your seasonings and broths. (Haven't tried this with pork yet; but considering the existence of molé, I expect it to work with chicken too.)

Dry sherry in tomato sauce, soups, or anything with beef in it.

Soy sauce makes everything better. If there is some kind of sauce or broth just add a little bit. The extra salt and umami flavor elevate everything. Doesn't matter the cuisine. It goes great in burgers

It's not that wild, but I absolutely LOVE blue cheese in a burger.

Worcestershire sauce in tuna. It is delicious.

I find a lot of dishes are just better with oregano.

hominy in chili

Balance acidity, that's pretty much how to make every sauce delicious. Per OP's suggestion, that free glutamate punch also helps.

Other than MSG - garlic powder, lemon pepper, paprika, and gochugaru. Almost everything I cook has those 4 put in, with only the lemon pepper reduced if citrus is not part of the dish.

Recently discovered the wonders of yeasty flakes, never thought to put it in sauces (only sprinkles) so I will give this a go, thanks!

My ultimate sprinkly pasta topping is a mixture of grated cheese, crushed Salted crisps, yeast flakes, fresh basil, hot sauce, and Japanese shichimi.

I don't know about "better", but I've been experimenting with adding bitter chocolate to my indian curries. The thinking being, some masalas are a bit like mole if you squint (yes, I know most moles don't actually contain chocolate). Balancing out the bittersweetness has been challenging, especially given that the tomatoes I can get around here are already quite sweet. It also affects how much lemon juice or amchoor is needed. I'm not quite convinced yet that it's a good idea lol.

Almost all of my barbecue rubs have black garlic salt/pepper. Make it myself.