I use H&R and they are perfect. Good pricing (under 275USD from tirerack) good quality.
H&R is a German company and Porsche usus their springs in the cars. Also BMW racing team using H&R coilovers. That was enough proof for me. A little more aggressive then Eibach F:1.25" R:1.00" . Clearance ? well with a CSI front spoiler there is cca. 3" on the front which is enough (on the steet) but never ever think about going on the dirt...

Eibach is good but on back-order most of the time (price $325.00)
Dinan - ??? know info, but as everybody says - very expensive and probably a good quality.
also there is a BMP and racing Dynamics springs, both supposed to be good.