This could go on forever. The RTR Losi truggy is a great place to start. Just get the kit and nothing else and go run it and have fun and replace something if something needs being replaced. And ask for some servos for X-mas.
I don't know about where you live, but I think in a lot of places buggy-racing is more uptight, whereas truggy is a bit more relaxed. I personally like driving buggies more, because they're more agile, nimble, and quicker, but I loathe the uptightness of racing. At the end of the day it's a hobby, which entails a tremendous waste(face it, you're not saving for your kids' education or donating to a worthy charitable cause..) of money, however seriously you want to take it. So to the OP, don't overanalyze it, just go with your gut and have some fun..
Truggies look cooler too.