What is the main advantage of front wheel drive over rear wheel drive?

One advantage is that front wheel drive (FWD) cars have less drivetrain loss of the engine's power. In other Words, the horsepower rating that you read in magazines and advertisements isn't the real HP that makes it to the wheels since there is mechanical loss between the engine and the wheels. FWD cars have less distance between the engine and the wheels, so less power is lost.

Another advantage is fuel economy. Generally, FWD cars get better gas mileage. Just think of a typical FWD car- a Corolla- vs. a typical RWD car- a Ford F-150 or a Mustang.

Last advantage I can think of is its stability in snow. Contrary to popular belief, all-wheel drive isn't necessary to drive safely in the snow. FWD does well in the snow because so much engine weight is directly over the wheels that are driving the car.

Finally, FWD cars tend to understeer, which is usually seen as a bad thing by auto enthusiasts but can be considered a good thing by parents who want their kid driving a safer car. Understeer means that a car, when pushed to its turning limits, doesn't fishtail like a RWD sports car can but instead just kind of stops turning. It can encourage safer driving.

There are plenty of benefits of RWD that I won't get into here.