Everyone will just tell you the brand of car they run is the best so here goes.
The Team C TM4 is the best out of the box 4WD car! Why? Because you get all you need in the box and don't need to add anything to make it a very competitive and easy to drive and setup car. It is also one of the best value for money kits available. I'm sure there will be plenty of people who will say XB4, YZ4, K2 etc etc but from what I am seeing they all need some vital upgrades to get the best out of them where as the TM4 comes with it all.
Just my opinion of course.