it depends on how much you want to spend.
I have the Mugen Pro Spec which is a very well crafted machine. They handle very well. They jump so easy and corner so smooth you cant go wrong.
I had the Jammin RTR and never could get it to hook up the way I wanted it. It was fast and I won some races with it but I guess because it was RTR was what was wrong with it.
Money is not the issue quality and reliabilty is.
Jammin' RTR is not the same as the factory team model which has a lot of additional quality parts.
The Hyper 8 is interesting though but it is down to these three and that is the reason for this thread.
Originally I had no question but to buy the MBX5 but the technology is about 2 to 3 years old but still might be ahead of the game.
I just don't want to buy one only to have it out dated in a couple of months.
Im not a big fan of Ofna (Jammin). I once read a post that Ofna uses nylon rather then plastic parts. Nylon has more flex but binds with metal.
The Pro Spec has alot of hopups. All brands have a flaw in some form or another. Look and all three of the Pro kits. See which "looks" better designed in your eyes.
Myself I drove a MBX5 last year and loved the control I had with it. I knew the person that owned the buggy and knew he did not have it setup right but it still felt GREAT. Plus I really like the clean look of the design.
Before I got my Mugen 3mo. ago. I went to the threads of all the buggies I thought about buying to see all the flaws I have to deal with.