So there really isn't a "Best" drive train. It really is what the team prefers, or works best with. My team has done a 4 wheel tank drive using 2 speed shifters in the long configuration. Our drive train is very sturdy, and is great at pushing other robots out of the way. We have been using our design for the past two years, and have had no complaints.
A drive train that I personally want to design, test, and see how well it fares compared to our current is swerve drive.
P.S. If anyone saw 4471's robot at championship, that's our twin, both teams had difficulties with playing offense, so we were a defensive robot, and were pretty good at it honestly.