The ideal type and size of AC for your room depends on the size of your room, the number of appliances in the room, the number of people using the room, the city in which you reside, and your spending capacity mainly.
Also, you need to refer to the BTU capacity of the AC. BTU or British Thermal Units refers to the amount of heat removed by the AC unit in one hour. 1 ton AC equals 12,000 BTUs and so on, this means higher the BTU means the air conditioner can cool much faster and more area. In case, you are still confused; you can approach the AC installation expert who can guide you through the same. Remember, an oversized AC will consume more power and inflate your electricity bills while an undersized AC will not offer the desired cooling.