Seems like some people are posting their favorite or what they think the best sandwich is, as opposed to what the OP is asking.
On a cold rainy day, with ingredients already on hand....my comfort food go-to sandwich would probably be a grilled cheese with ketchup and mustard, or sometimes pasta sauce. And some days when I'm feeling especially weird, I'd crave a PB&J with a slice of unmelted cheese. Yeah, I know...I'm strange.
Toasted honey wheat or everything bagel, turkey, lettuce, tomato, cucumber slices, cream cheese, and maybe a little bacon if I feel like it. Jalapeño cream cheese also works well if I'm going with the everything bagel.
I used to have this as a meal all the time before I started cooking stuff. I would always flatten the sandwich right after putting the chips in. You have to eat it right after making it though, or else the chips get soggy and disgusting.
Probably the last time I put effort into creating a sandwich. Brined panko fried chicken on a soft roll with mashed potatoes and gravy, cucumbers, tomatoes, and finished with a garlic lime aoli. Only time I'll eat tomatoes. I miss it.
I haven't had this in nearly a year as I'm a recovering fat ass but I used to love French stick with butter and Marmite with salt and vinegar crisps crushed up, vinegar goes so well with Marmite.