Well out of the choices I'd say get the X2
D8 is a good buggy but I've seen a few run and they are one of those buggies that if your new they are a pain
The RC8 I've heard has been having some fuel tank issues
X2 is the only buggy I've heard that hasn't had any problems and I've seen a couple run and they are really consistent
but if I were you I'd get a Losi