I could name several that I like. For subway, you need a footlong meatball with mayo and parmesan cheese. For Chick Fil A it's the #1 with no pickles. Arbys sometimes has the Arby Q. Just to show my age, I remember the Arby Q as a regular item. I like the chicken parmesan from Burger King. BBQ from DQ is good. If McDonalds is forced on me, ketchup only McDouble.
If you aren't hungry by the time you share yours, there's something wrong.