There’s a place in my heart (and mouth) for both thin/smash and thick/pub styles. 5-6 oz is the sweet spot, so give me a double if it’s a smash burger. And give it to me rare if it’s thick.
I like cheese (just about any kind, but I’m partial to a slice of swiss and a slice of American together) on both styles but will eat without. Sometimes cheese choice depends on other toppings/condiments.
Bun/bread has to be flavorful in and of itself and proportionately sized to the burger. Do not give me a 2" thick bun with a 2 oz. patty. If the bun sucks I will just eat the burger/toppings with a fork. I tend to like brioche or a good potato roll. No english muffins or anything crusty/hard to bite through. Buttery rye for a patty melt, obviously.
No raw vegetables. Ever. If I want a salad, I’ll have one on the side. Caramelized onions, sautéed mushrooms, deep fried jalapeños or onion straws, etc. are all fine, depending on my mood. Sometimes pickle slices or pickled onions.
Bacon is acceptable but not always necessary, especially if the beef is really good or the bacon is mediocre. I find most other meat add-ons detract from the burger itself (i.e. pulled pork, sliced brisket, etc.).
Last and perhaps most importantly, condiments. Keep ketchup the f*ck away from my burger, please. Mayonnaise is a must, particularly with chopped green olives in it (the olive burger is a mid-Michigan thing I grew up with). Mustard if I’m in the mood. Dijonnaise or other flavored mayos/aiolis (Sriracha, chipotle, garlic, etc.) may also be welcome depending on the flavor profile of cheese/toppings. Bacon jam or “big mac” sauce if I’ve made them myself so I know they’re not too sweet. I also love blue cheese salad dressing on a burger, especially a patty melt. Generally no more than one or two condiments, though - too many just take over the flavor of the burger.
All of that said, my favorite combo to make at home is a 6 oz pub on toasted brioche, cooked rare, with swiss/American, caramelized onions and green olive mayonnaise. Bacon optional.