I am using Carrier window AC of 1.5 ton capacity for the past 2 years. I find it pretty good. so far it has not asked for any maintenance. It is slightly more expensive than its peers in the market, but still it is a value buy.
One thing that I don’t like about it is that when I start it or switch it off, then it makes a bit of sound but in terms of cooling it is awesome. All in all, its a good buy:)