Not that I've been in all that many, but my vote is for Red Shoes Billiards in Alsip, IL, a near south suburb of Chicago. And the great thing is .... it's still open!. Very nice and well-maintained Gold Crowns, strong players, frequent tournaments, a bar with a very good though limited grill menu, no video arcade, no karaoke, a jukebox that plays only Frank Sinatra (not really), and great management. It's the action place in Chicago but a non-action guy like me has always felt welcome. Plus it has a really nice straight pool league.
The best looking place I've ever played in, and probably the best looking pool room anywhere, is the Illinois Billiard Club in Willow Springs, IL, a southwest suburb of Chicago. It's a bit like a museum with all kinds of displays and old photos of the greats of both pool and billiards. It's a private club. It also has a really nice straight pool league.