Asklemmy

Marmite.

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

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

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.

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.

New Mexico hatch Green chilies on everything.

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.

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

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

Bog standard "all purpose seasoning" in mac n cheese. Just elevates the whole thing.

Worcestershire sauce in tuna. It is delicious.

Dashi. Makes dishes get a lot of umami.

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

When I make quesadillas, I put a thin layer of this really good chipotle sauce on the tortilla before I start adding the ingredients. Plus, butter for browning the tortilla always trumps cooking spray. Finally, when browning the meat, there’s a sweet and spicy sauce I’ll put in the pan along with some honey to finish browning the meat. Adds a layer of sticky goodness.

Pumpkin pie. Add cardamom.

Ground fennel seed.

People use it for chicken, fish and broth and it's great in all of them but it realy shines in salads.

I used to be just like you, not really liking salads. They were always just a side dish or something to eat when I wanted to be "healthy". But that changed when I started adding fennel seed.

Now, whenever I make salad I start by adding a ton of FS, think "shit, I added too much", sit down to eat it only to get back up amd add more.

Sliced watermelon with Tajin spice is the food of the gods.