My experience with Gree Invertor is exceptionally good.
Yes, its overpriced, but what I have learnt that its one of the few brands that provide full cooling capacity.
I keep the thermostat at 26 deg which provides sufficient cooling and saving.
As a general rule always remember for a typical bedroom should have 1.5 ton airconditioner. The benefit is that it will cool quicker and maintain temperature better hence maximize your savings.
Stay away from 1 ton ACs, they can only work on ground floor in shaded rooms