After so much thinking and research, I finally bought LG 1.5 ton window ac (lwa 5cs3f).I have been using it for 1 month. My room is 150 sqft, west facing, lot of isolation during afternoon. But ac takes 20 mins to bring the temperature to 23 c. Rating is 3 star with err of 3.01, maximum power consumption is 1610 watts, 200 watts less than a 2 star ac, and with rapid cooling, it saves power too.
I use it for 7-8 hrs a day and on electric meter it never exceeds more than 9 units.I bought it for 24200, though now it is 1000 bucks cheaper. Worth a buy!