Not really sure if it qualifies as a sandwich..but I really like the Gyro wrap you can get at the Greek pizza shops. It's some sort of shaved meat, lettuce, tomato, and a sour cream like dressing. I probably don't want to know what the meat actually is.. if that's not available when I get a sandwich.. I revert to the plain old Italian sub. ..no onions.
A few years ago I was tailgating at a Patriots game. A group of 30 or so season ticket holders has their own little section where they all put on a feast before every game.. I was very fortunate to be included. The friend I was with brought marinated fillet minion burgers for the grill. .. these were about 1/2" thick before cooking, marinated in a Italian dressing of some sort with salt and pepper. Sliced in the middle before grilling, then added a piece of American cheese on a grilled and buttered bun.... these things melt in your mouth. .. that would be my go to if available in a sandwich shop... but have never seen them anywhere else.