Big ups to Glenn's as well. Stellar biscuits and gravy, and really really great potato pancakes.
I've heard great things but have yet to make it up to Over Easy, just a bit north.
Glenn's Diner
1820 W Montrose Ave
Chicago, IL 60613-1008
(773) 506-1720
Over Easy
4943 N Damen Ave
Chicago, IL 60625
(773) 506-2605