I got myself a Cobb AP 2 weeks ago.
My main reasons for choosing Cobb are the ease of use, portability and able to maintain M button functionality. And it's good to have someone like Peter at Advan who has plenty of knowledge and able to do custom tune with Cobb down the track.
I started with the stage 1 sport map and didn't really feel much changes but when I loaded up stage 1 Aggressive stock throttle map, I am loving it. Better low end torque and throttle response and the M button still work.
Here's the throttle map of linear throttle vs stock throttle. Photos are from Cobb tuning.