Rear wheel drive FTW!
Real wheel drive has a bunch of advantages. The first is the cool factor. Having a big hub in the front just looks wrong. But on a more practicle side, there is the efficancy issue to wory about. as you ride, you move the front wheel back and forth in small amounts to maintain balance. If you draw a straight line down your path, you would see that the front wheel is constantly crossing that line by small amounts. The back wheel, however, tracks behind, and would continue on with little movement from that line. If you take the line your front wheel travels and stretched it out, the average rider's would be 5% more. This is one of the biggest reasons why quality speedometers are measured from the rear wheel despite the need for extra wire. For an Ebike, it means the motor has to drive 5% farther to make the bike cover the same distance.
Have you ever lost traction on the front wheel of a bike? Most kids learn how to skid therte rear tire within months of learning to ride, and sidewalks and streets around schools are in a constant state of disfigurment with skidmarks from kisd powersliding and skidding there bikes around for fun. On a rear wheel, its easy to controll a skid, as the skidding wheel is trailing, and you still have the ability to steer. Skid on a front wheel, though, and you loose all controll. since the front wheel is also the primary means of balance, and since gravity is conspiring against you at 9meters a second squared, the result of most skids is usualy a quick meeting with the street, or at the very least brown shorts.
Having the power in the front wheel using part of your traction as a means of propulsion means you are closer to the limit of traction all the time. Having the mass of the motor also means you'll have more mass and momentum to deal with to try to correct any problem.
And its harder to ride up curbs.
And it's harder to pull the wheel up or light for cruising over drains, railroad tracks, sticks in the road, ect.
And it's hard to lift the front wheel into a bikerack
And... the list goes on.
And then there are all the dangers associated with front fork failures and losing wheels. this post is turning into a chapter. I'll leave that for someone else.