My vote goes to Eleven City Diner at 1112 S. Wabash south of the Loop and a block from Michigan Av as well as the El. It might lack the "atmosphere" of Manny's but the food is pretty good and quite authentic(I am a Jewish guy and a deli goer from way back). It is owned by a young guy who traveled the country going to various delicatessans and incorporated the best of what he experienced into this restaurant. IMHO definitely worth a try.
Jim
I have engaged many cities in this wide,wonderful world but my heart belongs to Chicago