In the Division Street hotspot area of Ukrainian Village, Smoke Daddy is by far the best BBQ I've had since returning to Chicago. (Yes, it finally unseated the long-standing champion, Fat Willy's BBQ.)
However, Smoke Daddy is more bar (and live music venue) than restaurant, so you need check your mindset before deciding on which to visit. If you're only considering the food, go for Smoke Daddy. If you want a nicer, more traditional restaurant setting, the Fat Willy is your choice. Either way, be prepared for good BBQ.