I've got no direct experience with the Kyosho RTR buggy. However, I have heard that the quality of the RTR version is nowhere near what it is in the Kyosho kits. I've got a Kanai 3 and it is a very nice buggy. Top quality materials throughout and tough to break.
My other buggy is a Hyper 7 PCR. Hyper 7's are nice buggies as well; I personally think the materials don't quite measure up to the top level buggies but they handle well and are a lot of fun to drive. The new Hyper 7 TQ "Black" is really a pretty sweet ride, especially for $300 US RTR.
So my vote would be for the Hyper 7. Good luck with whichever one you choose.