I have had a few kits over the years.
Two different HnR cup kits, feel totally different too, one i got new and the other came with a car, i just don't think they last that long, as the one that came on the car was awful and the new set has lasted well and ride so much better, and they are bloody expensive now. So much better out there for the money.
Had Koni's and eibach springs on my derby which ride very well, however don't drop the car much at all, and give a little reverse rake without lowering spring top caps.
Got a new set of Billies and KW springs which promise to be good, but haven't run them yet. I have a pair of the B8's with eibach springs on the rear of my derby currently and its very nice, so with the new shocks and KW springs i am hoping for the right amount of lows and a very good ride
Also had those cheap coilovers, blew one rear shock up after only a few thousand miles and replacements are silly expensive, the fronts are too hard for road use and would suit a track only in my opion.
Its a hole package and i would look at the TCA and steering arms too, also look into the rear axle bushes and top mounts as they tighten things up nicely, which is what i am doing with my daily mk2 G40 with the billies, and a stage 2 subframe (if it fits)