I'm partial to the Serpent S411 myself, but a big part of getting the kit was that there were guys already running the car at the track, and parts are much cheaper than Xray. Parts support at the LHS doesn't exist unless you race Traxxas here so I've been ordering all my spares from Rcmart and Rcmarket without issue.
Another car to consider would be the soon to be available Durango DETC410. It looks to be cheaper than the others, comes with great upgrades over the other brands (like djc's) and parts should be cheap and readily available.
Whatever you go though, enjoy it!
Serpent S411 Eryx 2.0 (Mod)
Serpent S411 Eryx 3.0 (USGT)
Serpent S411 Eryx 4.0 (Stock)
HPI RS4 Pro (shelf queen)