Chap’s wasn’t as good on my second visit as it was on my first, a few years ago (pre-DD&Ds!). My only visit to Dinic’s was also prior to their being named the top sandwich in America, and I liked what I had there, too.
 
Next time you are in Baltimore, you might want to give Pioneer Pit Beef a try. I can’t say that this is my best picture, but should give you a decent enough idea….