Automatic vs. Manual Shift - Which is better?
The answer is not an easy one, because each transmission is, if you'll pardon the expression, geared to different styles of driving.
WHAT'S THE DIFFERENCE?
A transmission is required in a car for essentially the same reasons why bicycles have ten gears or more. A human's leg power is restricted to a certain range of power and rotation speed. To move a bicycle faster and still keep your feet from flying off the pedals, you must continuously change the gear ratio on the chain to the rear wheel.
In a car, the engine produces usable torque (pulling power) over a relatively limited engine revolution (r.p.m.) range. Transmissions are machines that alter, through a series of gears, the rotational connection between the engine and the drive wheels. In this way, the maximum power of the engine is optimized to the various speeds and loads that the car requires.
An Automatic transmission makes the gear changes automatically, relying on measures of the engine speed and the pressure on the throttle pedal. A Manual transmission (sometimes called a Standard transmission) relies solely on the driver for these adjustments, who controls it by use of the throttle, clutch, and gearshift lever.
WHAT ARE THE ADVANTAGES?
That depends strictly on how involved you want your driving to be. Guiding a car down the road can be divided into two separate but essential skills:
Maneuvering along roads and dealing with other cars, traffic, rules, pedestrians, etc.
Controlling the physical motion of the car - i.e. operating the car as a machine.
An automatic transmission lets you concentrate on A by making B relatively simple. The disadvantage is reduced control of the car. A manual transmission divides your attention more evenly between A and B because B is more complicated. The advantage is more control of the car.
Driving an automatic car is easier in the sense that you don't have to worry about operating the car as a machine, although when that kind of control is necessary, it isn't always there. Driving a manual shift car becomes a continuous, unending exercise, requiring constant attention, but allowing you great control over speed and acceleration.
As far as performance is concerned (acceleration, fuel economy), the driver of a manual shift car has more direct control over these aspects than one in an automatic car. The sportier and higher performance cars are usually manual shift, as are race cars.