Like BB, it depends on the theme and the meat used. Often, we have basic grilled burgers with Montreal or Misty's (local business) seasoning. Red onion, tomato, lettuce, pickles, and condiments. DH butters and grills the buns to make them crispy and so good!
This winter, we made Pioneer Woman's sliders with sauted mushrooms and onions, Worchestershire sauce in the meat, swiss cheese and her spicy fry sauce (mayo, cayenne pepper). Very, very good but rich!
I also like turkey burgers topped with guacamole or avacado, red onion, pepper jack cheese/cheddar cheese and lettuce. I season the turkey with a mixture of cumin/chili powder.
Yum! Fun post!