Who makes the best 4WD system is certainly up for debate, but what is the best 4WD system? That question seems like it should have a realistic answer based on physics. The best 4WD system, in my opinion, is the system that gives you the least likelihood of getting stuck. In nerd-speak, it's able to put down the greatest percentage of available torque.
So how do you put down the greatest amount of torque? Well that requires a clever 4WD system, that's able to change based on conditions. One such change vital for off-roading is the ability to lock up differentials. What's the difference between an open and a locked differential? An open differential allows for uneven wheel speeds, but always maintains equal torque. A locked differential does the opposite, locking wheel speed together, but allowing for unequal torque distribution. Torque is sent where grip allows for the torque to be sent. Check out the video for full details, as well as examples of vehicles which I would consider have the best 4WD systems.