My best advice is to try and test out some cars you like the look of.
It's all well people telling you "Oh yeah such a person piloted such a car to victory on such a championship" but to you that means naff all as they'll be able to do good with any car.
Try and get to a local club or two and see if you can have a go of some various buggies.
A strong point to look for is spares availability for the chosen car, it's no good if you cant get spares either locally or quickly online as it can eventually lead to missed races e.t.c.
Going off points such as popularity, spares availability and what I've heard (or tried), these cars seem a good choice: Associated B44, Kyosho Lazer ZX-5 FS/2, Schumacher Cat SX/2. People will obviously argue with these choices, but the choices reflect the points of support, popularity and good critique.
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