I have experiece on E90s with H&R Sports/Yellows, Eibach/FSD, and PSS9s.
If I rated them, the H&R/Yellows were the worst combo. Ride was always harsh, even on soft settings and performance was not up to par at the softer settings. 1-1.5 turns made the cornering awesome, but the ride, well, ouch is all that comes to mind. It was tolerable, but certainly not ideal.
Next best was Eibach/FSD. Decent ride quality, with good looks and good handling. The only real drawback was when carrying passengers. With two in the rear the car lost its composure. It must have something to do with the way the shocks work as they are pretty unique. But for the price, and very good combo, and I would purchase again.
The PSS9s take the cake. Ride ride quality is awesome, and the cornering is a thing of beauty. On this E90 I have yet to install my H&R sways, but can only imagine that with the addition of the front/rear sways, handling will be amazing. I have them set pretty soft, 7f/5r. and its a decent setting even as is. There is some roll which is not a bad thing, but you truly feel you are driving a luxury sports car. Great handling with a great ride. I rarely feel abused with this setup as I did daily with the H&R/Yellows. But, the cost is pretty high, with install they were nearly 2k, and that certainly is a drawback for many, including myself.
Well, thats my .02,