Are JEMs better than RGs?
Yes... and No
A top of the line JEM is just different to a top of the line RG. At this level it's not about "better" it's about prefer. What woods you prefer, what pickups you prefer, what visual style you prefer etc. etc. etc.
Is a JEM7VWH "better" than an RG170. I'd say yes. Better quality woods better quality hardware etc. etc. etc.