What brand air conditioner should I choose? Are they all pretty much the same

  No, not all are the same. There are a variety of low cost “clones” available but they often prove to be unable to handle the nations summers. Trane Air Conditioners have required the fewest repairs during 16 of the last 18 years and did not fall below #2 or #3 during the other 2 years. Trane remains the only manufacturer to build their own compressors throughout their residential and light commercial products. In fact all Trane components are either made by or manufactured specifically for the Trane product they come in. Matched components and matched systems… the best way to assure everything works together as they should.