I to went with the Bilstein B12 kit and am very happy with it. Lowers the car nicely with a good stance with decent wheels and spacers applied.
The ride is much more responsive now, yet doesn't feel crash at all. I think the overall feel is more comfortable than my original SE suspension, although that might be cos it had done 80k.
I would def recommend the bilstein kit if you're looking to replace springs and shocks without compromising the ride. There's a video on youtube comparing the eibach spring options on a 3 series bmw. Helps when considering which spring to go for.