What foods should have a "best after" date?

Chili for sure. Most stews will end up better after at least a few hours of being in the fridge, but overnight is better. Soups, not so much that I've ever noticed.

I guess you can argue that pickles and fermented foods need a best after date, since they kinda do, but the truth is that the process of pickling or fermenting is the equivalent of cooking whatever it is, so I don't think it counts the same. However, most pickles and ferments do get better around a week or so after the initial process is done and they're shoved into storage.

Sardines. You can keep them one or two years after buying them and they’re supposedly better. At least that’s what some restaurants do.

You can also buy 4 years old cans, but they can be expensive.

So, as has already been stated—soup/stew-y foods (I was thinking pozole specifically).

But I used to get these chocolate caramels from a bakery near my house, and if you let them sit for six months or so they dried out and turned into something so incredibly magical—tender, delicate, light as air outside with just a bit of soft middle. Man, I miss those.

Also citrus segments get a nice crisp bite if they sit around for an hour drying out after you peel them.

Finally, cheetos are best after spending an hour in the sun on a hot dashboard. (It doesn’t work to put them in the microwave, 10 year old me tried that.)

Those chocolate caramels are the kind of answers I had in mind for this question. Now I want to try 'em...

Homemade soup always tastes better the second day, especially Mennonite Plautdietsch Sommaborscht and Komstborscht! Guess it gives the flavours a chance to mingle or something.