i dont like the rkm. it was originally marketed as 'identical to genuine HKS valve'. Then later it was found out that it was not....not a fan of knock offs.
I've seriously had about every valve out there... My favorite was the HKS and Turbosmart compact dual port (what I've ran now forever). Only reason I traded the HKS in was because the recirc line would not fit right with my FMIC setup and I got tired of running VTA. SU/turbosmart also has a new/cheaper bpv. As far as value....forge and the new TS one seem to be where it's at. I'm personally not a fan of the forge sound, but it does function well and is a good value. From what I've seen the new TS one sounds pretty much like stock, maybe a little louder/crisper blow off noise.