I just switched from BC Coilovers back to stock shocks with H&R springs. The coilovers were a nightmare to deal with. Absolutely s***-poor ride quality, lots of noise, components fail frequently (mounts, shocks, etc.) and just requires a lot of maintenance overall. The center tightening nuts and spacers have been know to take a lot of wear, to the point where the metal becomes compromised. See:
switching-from-bc-racing-coilovers-to-e ... 72505.html
The ride on BC's is very stiff. So stiff that if I'm on -10 from hard on the damping setting and hit a pothole, I have been knocked out of my seat and hit my head on the roof.
A $1000 purchase turned in $3000 of parts and labor over the course of 2 years.
I can't speak for other brands of coilovers, but for the most part these are made for racing and simply require a great deal of maintenance.