Here are 5 quick reason why manual transmissions are better than automatic transmissions.
1. Manual transmission have fewer maintainace cost compared to automatic transmission. Automatic cars requires regular change of fluids and replacement of filters. They have slippage and high fluid operating at high temperature in normal condition. This cause the fluid to degrade faster than in manual.
2. There are no delays in manual than automatic. In automatic, you will step on the gas waiting for the transmission to select the appropriate gear so as to select desired acceleration. In manual, there is direct connection between rpm engine and tire speed.
3. You will have total control of the car in manual than in automatic transmission. With shifting of gears, you will be in control of the car. Manual allows you drive the car or engine with higher rpm range than usual.
4. There are more power to the wheel. Percentage of power loss in manual are less than in automatic transmission that will prevent your car from propelling fast. Power loss occurs from slippage in torque converter. If their is power loss in manual, the power will be sent to the tire by manual gear box.
5. Engine modifications are easier. Modifying an automatic engine can lead to power loss and degrading driving quality because factors like changing vacuum and electronic control, should be considered. In manual, modifications are easier and come with benefits in power and control.
Automatic transmission are also cool and best but Manual transmission are coolest. You can add other advantages of Manual transmission if you agree with this and also you can criticize by giving the disadvantages of manual on comments section. I guess that's why it's commonly used in Safari Rally Competition.