I have been to a few of the service centers in the western suburbs with the best one being Laurel Bmw in Westmont. Jay Buis is the SA i have been using and he is great. Always goes the extra mile.
The worst place, by far, is Elmhurst BMW. One of their managers, "Corey", was a complete jerk. I was trying to explain the lag to him, and he argued with me. Extremely confrontational. Never went there again.
Bill Jacobs doesn't have any personal touch. Always got a vibe that I was getting ripped off there.
So, Laurel is the place I choose to go to...