Aside from all the Losi love (deservedly so, it's a hell of a starter package) I've seen two schools of thought:
* Buy what your local hobby shop and racers you respect drive. You'll have good parts support and help in setup. It also can't be underestimated that more than likely someone will have a spare part in case you break something
* Buy what you have your heart set on. I read a bunch of online reviews and came to the conclusion that I was in love with the Z01-B. Everyone at my local track runs either the Losi or Mugen. However, the good guys drive a lot cleaner than I do and can use the "twitchiness" to their advantage where it causes me grief (inherent instability ~= more nimble, IMO).
I went with the second approach and have not regretted my decision. I don't have a local hobby shop that supports 1/8th scale, so I would have had to buy online regardless. A number of people have been impressed with the build quality and I can still get help with setup problems (the best drivers can tune a bathtub on wheels).