As Krupicka suggests, you're not going to play much _in_ Chicago (one course at IIT? one of these days I'll try it). And, the Chicago area's a pretty big place. So, it might help to know where you're based, or hanging out, or want to hang out.
I'll agree with Krupicka that for disc golf alone, you could do a lot worse than the Joliet area (kind of the far SW suburbs). But, there's a lot of disc golf to be had within e.g. an hour of downtown.
If you're considering NW Indiana (and why not? not really much further than Joliet from downtown Chicago) I'll give a shout out to Rogers Lakewood in Valparaiso. (Particularly for those who e.g. might be at Lemon Lake to watch Pro Worlds, but also want to _play_ a little golf!)
In Joliet, I've heard great things about Highland Park and enjoyed playing West Park.
Eagle Ridge in Oswego was also high quality.
The Oaks, as has been said, is OK. Maybe not a destination course in quite the same way as e.g. Highland Park might be.