Wow, you're all over the board here.
The Kyosho is a 1/10 4wd RTR, the HPI is a 1/8 4wd RTR and the Ve8 is a kit.
Just what do you wish to do with it? Race, bash, shelf queen?
How much are you willing to spend? As little as possible then of your choices the Kyosho fits the bill. Do you want the experience of building, outfitting and painting a kit then the Ve8 is your choice (it's also a very capable racer if equipped properly). The HPI fits in between, it has all the racing drivetrain of the HB D8 and the ease of an RTR.
I have a Ve8 but I've been racing 1/8 buggy and truggy for nearly ten years and owned several buggies the latest is a Kyosho MP777 SP2 and a Losi 8ight-T. I've raced 1/10 buggy and stadium truck for twenty years. I picked the Ve8 brcause I hate RTR and find that I end up replacing almost everything to race them. The Ve8 is made for racing (weakest point is the chassis craking in the middle) and your choice of gear makes it less expensive in the long run than replacing all the electronics (yes an AM radio works and the minimal servo will turn the wheels but those are the least costly components they put in a RTR). The other thing is that if you build it you know how to fix and adjust it. I have bought RTRs in the past, Losi and Traxxas, and everyone required it to be stripped down and rebuilt so the parts don't fall off or leak out all the fluids.