If your list is down to those 3, I would narrow it to the Xray EC and Losi 8. From there buy what you have support for at your track or what you think you would enjoy more. Both are some of the most well built and capable vehicles, and like any well built buggy, can take a beating by The Punisher himself.
I chose the Losi 8 because I like that it doesn't look "phat" and because a good friend drives one, so we can share parts and tips. Now the only thing different about he and I are the damn servos! Lets see: Team Magic F8 bag, Futaba 3PKS w/ FASST, C6BB 92mm header 2045 pipe. He uses JR servos and I will shortly be tossing my Airtronics 358s for the JR 9100S. It makes it quite nice to be able to compare our cars, AND now we cant blame our loss on anything but ourselves! Again, buy what you think you would enjoy more, its a hobby, so go have fun!