The kits will ALWAYS be better. The RTR's cut corners usually with cheaper radio and servos as well as stamped aluminum instead of milled or carbon fiber. In the long run it will cost MUCH more to replace the lesser quality parts. That said, RTR's do have there place. But the frustration they bring can turn some people off. If you go that route you should plan on immediatley upgrading the servo's. Get the best you can afford. Never skimp ther or you will pay for it. Also, there is no better way to learn your kit than to build it yourself. I would recommend the Xray 808. It is very easy to get setups on it and is THE most durable buggy out there. The price is a bit more but the fact that you never are never replacing broken parts saves you in the long run. For a RTR I would probably get the Losi 2.0 as much as it hurts me to say it! LOL
Oh yeah, get a buggy first then a truggy. It will make you a better driver.