I have a B4. Parts are easy to find and the car is quite durable. It is also the current 2wd world champion. Team Losi is also a very good car. The only concern for american buggies is that they use imperial screws and bearings.
If you want metric, you have to look into Japanese cars like HB or Kyosho or Tamiya. Out of the 3, Kyosho has the better car.