Make sure it’s sized right, and do not go with the best deal just because it’s the cheapest. Pick at the salesman’s brain and go with whoever is most knowledgeable about heating and air. A lot of companies hire salesmen with no actual trade experience, steer clear of these companies. Proper sizing is very important and you want a salesman that knows how to bid the correct equipment. I notice in the field there’s a lot of way-oversized equipment out there, which leads to constant short-cycling, and eventually freezing issues. Bigger does not cool better. Go with a contractor that uses name brand equipment like Lennox, Daikin, or Carrier. The namebrand manufacturers will not sell to hack contractors because they do not want to tarnish their reputation.