I don’t know, I prefer the low effort theme of backyard burgers personally.
You smash that burger on the pan, flip around to season and then put a slice of cheddar on it. Few strips of crisp bacon, iceberg salad and tomato to garnish. I understand the appeal of well-made gourmet burgers, but it’s just not my homeburgers.
Chilli flakes and - like Elenthas said - cheese are a great addition to the mince-patty before you grill the meat. As for the rest of the burger, I’d recomment lightly toasting a brioche bun, pepperjack cheese, relish (homemade, if you have the time), bacon and a fried egg make the perfect burger for me.
I’m thinking about experimenting my low effort burgers with that ketchup-mayo mix. I tried it for the first time last week when I made some deep fried chicken (and also deepfried fries because we had so much batter) and honestly it was better than I expected.