Caplanskys or Free Times Cafe
Try both and report back. There are fans of both here on CH.
Caplansky's can be very inconsistent. When right, their sandwiches are sublime and hard to beat. When off (poorly cut, over salted, slow service, so the sandwich is not hot enough as examples) it can be extremely disappointing.
I haven't been to Free Times in a while. The smoked meat had been bagged and reheated in hot water. It was a good sandwich.
Free Times was darker and more intimate, while Caplansky's is bright.
Chacun a son gout!