Many brand are now launching many highly efficient five star rated ACs with included value added feature.so there are some point of view to buy a AC.
capacity should be consider depending on floor size of the room for AC is required for that.area 120140 sq.ft. will need 1 tone, 150180 sq.ft. need 1.5 ton like that.
energy efficiency ac come with star rated energy efficiency rating EER. unit with more stars will consume lesser electricity than one with lower star rating
air quality is important in ac.it is good with better filter to improve indoor air quality.it sure cooling performance and clean air.
4.cooling speed you may want to use variable speed for different time of day or many seasons.
5.brand carefully choose an ac brand which they fulfill your need of maximum energy saving through EER,
I hope this tips will helpful while buying a ac.
thank you.