Thats a no brainer.. you cant compare them like that. The coil-overs are much more expensive and their advantage is when you are at the track you can raise the front of the car to increase wieght distrobution. When launching that is a good thing.
Eibach's are good to improve the handling and getting rid of the "4x4 look" I suggest to buy the sportlines.. My prokit did not give me much of a drop. 3.4" in the rear..