I would say my favorite left overs are:
Spaghetti
BBQ's meat loaf.
I actually like the BBQ'd meat loaf more as a left over than fresh! That's why I make a 3-4 pound meat loaf.
I heat up a cast iron skillet and "scorch" them until there is a little crust. Especially with the meat loaf. Slice an inch thick, cajun seasoning, scorch, serve on garlic bread with some kind of fantastic hot sauce like Pepper Plant, see link below.
https://www.safeway.com/shop/product-details.105400447.html?cmpid=ps_swy_noc_ecom_goo_20200924_71700000073391208_58700007112002031_92700063970942081&gclid=Cj0KCQjw0K-HBhDDARIsAFJ6UGiLF9EUPwZ6fLyZ3R9u-HYENwwbKFUG1U4CaNTA-I3sIg5c9746McwaAsxvEALw_wcB&gclsrc=aw.ds