At home, I have mustard and relish or mustard and pickles at a minimum. Maybe lettuce and onion as well.
At a restaurant, I’ll eat what they give me, adding mustard if necessary.
Should be two choices of onion: grilled and raw. (I prefer them raw.)
We had a thread a few weeks ago about hamburger toppings.
I did some online research and came up with this list: Anchovies, avocado, baby greens, bacon, BBQ sauce, bean dip, black olives, black pepper, blue cheese, blue cheese dressing, boursin, bread and butter pickles, brie cheese, buffalo sauce, burger sauce, Caesar dressing, Cajun spices, candied apple slice, caramelized onions, cheddar cheese, chili, chili mayonnaise, Chinese five-spice, chives, cooked spinach, cranberry sauce, cream cheese, crunchy tostada, cucumber, cumin, Dijon mustard, dill pickle relish, dried onion soup mix, dried red peppers, fajita seasoning, feta cheese, fresh basil leaves, fresh spinach leaves, fried egg, fried green tomatoes, fried onions, garlic, garlic aioli, garlic cheese, garlic mustard mayonnaise, goat cheese, Gorgonzola cheese, Granny Smith apples, Greek yogurt sauce, green olives, grilled eggplant, grilled mushrooms, grilled onions, grilled peppers, grilled pineapple, Gruyere cheese, guacamole, gyro sauce, ham, hash brown, herbed mayo, heirloom tomato slices, Herb crusted Brie, herbed goat cheese, honey, honey mustard, horseradish, hot paprika, hot peppers, hot sauce, hummus, jalapeno cheese, jalapenos, jerk seasoning, ketchup, lettuce, lump crab meat, Manchego cheese, mango chili glaze, mango chutney, mango slices, marinara sauce, marinated red onions, mayo, mint leaves, Monterey Jack cheese, mozzarella cheese, mustard, Old Bay seasoning, olive tapenade, oregano leaves, papaya, Parmesan cheese, peanut butter, pepper jack cheese, pepperoni, pesto, pickled jalapeno, pico de gallo, pineapple slice, pizza sauce, potato chips, provolone cheese, red beets, red onions, red pesto, refried beans, roast beef, roasted balsamic onions, roasted red peppers, roasted tomatoes, sage pesto, salsa, sauerkraut, Serrano ham, shrimp scampi, smoked bacon, smoked Gruyere cheese, sour cream, soy-ginger sauce, spicy curry mayo, sprouts, sun-dried tomatoes, sweet & sour sauce, sweet mustard, sweet relish, Swiss cheese, tangy corn relish, Thousand Island dressing, tomato, truffle salt, wasabi mayo, watercress, wild mushroom sauce, Worcestershire sauce, and yellow onions.
Beetroot!
Well fried or poached egg is great in a burger. Ketchup (obviously). Slice of cheese. Lettuce. A small quantity of onions. Amazing.
Communist!
Cheese, tomato, pickles, mustard at minimum. Jalapenos if they are available (who doesn’t have pickled jalapenos at a burger cookout anyways?!!).
Depending upon my mood and where I’m eating, there are many topping combos that are acceptable to me.
On burgers cooked on the grill, a little Heinz 57, cheddar or cojack cheese, garden ripened tomato and dill pickle slices on an onion-poppyseed roll.
Home cooked indoors, mayo, creamy slaw or a schmear of guac, mustard, pickle relish, grilled onions and mushrooms and swiss cheese on toasted pumpernickel.
At a casual dining place, any number of specialty burgers, usually involving bacon and cheese.
At the drive thru, lettuce, pickle, mayo and tomato.
I’m pretty open to most toppings for the most part, with a few exceptions: onions must be steamed or grilled (more because raw onions will make me miserable) and no horseradish or sauces containing it.
Mustard, catsup, pickles, onion. Lettuce and tomato are good, too, but only if it’s a homegrown Indiana tomato slice. Store tomatoes won’t do.
Mayo on a burger is an abomination. Hell, mayo as a condiment is an abomination.
In Peru, putting an egg on a burger makes it a “Royal”.
Burgers without mayo are naked ;). It’s Miracle Whip that is the abomination.
Mayo ( usually ), Thousand Island dressing or some other closely related related condiment, lettuce, tomato, onion. Pretty simple. Cheese, bacon or mushrooms are options, but rarely pursued in my case. I really dislike pickles or relish on burgers. Ketchup and mustard are tolerable, but I won’t use them on any burger I assemble myself.
Meat may be doctored any of a number of ways. I had some damn good lemon-butter infused burgers awhile back at a friend’s house.
Plain, but you left off cheese. I love a good cheeseburger with just meat, cheese, and bun. The only other things I ever put on a burger are mushrooms (in which case the cheese should be Swiss), bacon (cheese should be cheddar or American), or Canadian bacon (again, the cheese must be Swiss).
A good CBS (Canadian Bacon and Swiss burger) is a thing of beauty and wonder, but I haven’t had one since college. (I don’t cook much, and I can never find any place where I can get one).
I like different things at different times.
Pesto, guacamole & Thai chili sauce are good additions.
Tapenade or tinned pineapple rings are good on chicken burgers
The standard Aussie burger from the local fish and chip place - lettuce, tomato, beetroot, fried onions and BBQ (a few people prefer tomato) sauce. Optional additions are any or all of cheese, bacon, fried egg and grilled pineapple. No mayo or anything else that I can think of.
How did pickles, one of the quintessential hamburger toppings, miss this list?
Anyhow, my standard burger is:
mustard, ketchup, onion, pickle
When I’m trying a burger for the first time, trying to establish a baseline, that’s what I go for.
I like lettuce, but not on my burgers. Tomatoes, unless they’re really fresh and not just the pink-tinged flavorless cellulose you get most of the time, also need to stay off my burger. I enjoy mayo in general, too, but, once again, keep it away from my hamburger. The only exception is the mayo-based special sauce on an In-N-Out burger.
Oh, a fried egg with a runny yolk is also fantastic, but only on the thicker style of burgers for me. That’s a bit overkill for a fast-food style 1/4-pound-or-less burger.
All those flavorless tomatoes should just be put directly into the compost pile. For a long time, I thought that I didn’t like tomatoes. Then I had a nice, fresh, ripe home grown tomato. Now I will eat tomato sandwiches if I can get good tomatoes.
I want mustard, cheese, and the patty on my burger. Sometimes I’ll take mayo as well, but I really like simple burgers the best. When I cook burgers at home, I usually put a little seasoned salt, garlic powder, and poultry seasoning on them. Yes, poultry seasoning, it’s good for more than poultry.
When I was working on the Naval Air Station in Jacksonville a bazillion years ago, I used to get a burger at one of the base grills. The patty was topped with swiss cheese and grilled onions and mushrooms, served on a bun spread with sour cream. It’s still a favorite of mine, although I don’t make it all that often. What made it especially good was that the onions and mushrooms were really buttery, and I don’t take a high enough dose of Lipitor to counteract it on a daily basis. 
If I make them at home, I use fairly low-fat beef (90/10, but nothing lower-fat.) and fat-free cheese which has the consistency of linoleum but tastes pretty good. I generally serve them plain with grilled veggies on the side.
If I go out for a burger, I’ll get a plain patty with lettuce, tomato and onion. No bun and no cheese. Sometimes, I’ll get a veggie burger with cheese and vegetables. I just find that most commercial burgers are too much.
[QUOTE=Lynn Bodoni;15176480 Now I will eat tomato sandwiches if I can get good tomatoes.[/QUOTE]
Oh, man, there are few things in life more simple and delicious than a tomato sandwich made from homegrown tomatoes.
Did you go into Burger King? What do they call a “whopper?”