I'm planning on replacing my York heat pump system in the next 4-6 weeks. I'd like to move to Natural Gas heat. I have two quotes from reputable businesses. One quoted a Trane XR17 air conditioner with a Trane S9X2 gas furnace, the other is a Tempstar TVA936GKA air conditioner and a F96CTN08017 furnace. Are there advantages of one over the other? Which brand is more reliable or has a lower Total Cost of Ownership? Thanks!