Personally I don't seek out Jimmy John's, but when up for a sandwich and not near any good delis, Jimmy John's is a far cut above Subway, and = with potbelly's in my opinion (Potbellys is the one I don't understand the hype about, decent mid tier sandwich but that's it)

Jimmy John's meat is usually a nice leap up from the pre-sliced food service logs of beaks & cheeks that Subway uses.

Speaking of good meats, each Jersey Mike's store I've been to cooks off their own roast beef, yes the same real roast beef you & I buy in a store & cook off (sometimes an eye of round, bottom round, etc). There is NO large chain that I know of that cooks off their own meat at each store. As a result the roast beef at Jersey Mike's is my go to if I'm in a chain only area & don't know of a good local deli. All the other meats at Jersey Mike's are made by the usual suspects of mass deli meat manufacturers.