Each of us must have a personal standard based on some experience that will likely never be repeated in its entirety, but which still serves as the paragon by which all others will be measured.
Mine is from my pre-school years. It was a little grill in a bus station where we would go after church on Sunday evenings.
The plain bun, no sesame seeds, was lightly toasted on the inside.There would have been a light coating of mustard and mayo on the bun. A couple leaves of fresh iceberg lettuce. Equally thick slices (roughly 1/4" each) of tomato and onion. The 3/8" patty was not quite well-done, still juicy. Later on I added American cheese as a request item.
I was out of college when the early version of Wendy’s had as close as anything had until then. And a short-lived Backyard Burger in the neighborhood did well for a few months. But if I want “the real thing” now I have to grill it myself and do all the prep work to conform as much as I can to that ideal from childhood.