I'm kinda sorta looking for ideas in this thread but, mine would be,
Medium rare bacon, nice and chewy, over a freshly sliced tomato and an ice burg lettuce leaf on a hamburger bun. Oh, with tons of Miracle Whip on it oozing out the sides.
If you've never had a BLT on a hamburger bun, you don't know what your missing. It's the only way I've ever eaten them.
I'm also very partial to a sliced chicken breast with tomato and avacado with a lettuce leaf on it, too. And, of course, lots of Miracle Whip.