I'm a Lennox fan, but was very in-impressed with the sales person that they sent to my sister's house. I was taking care of selecting the contractor for her because I spent many years in the HVAC industry.
LP quoted a 4 ton AC with gas furnace in a 1200 sq. ft. house with no western windows. Also, a big one is no natural gas in the neighborhood. I wanted a heat pump installed, the builder cut corners and went straight AC with electric heat. Much cheaper to heat with a HP.
I had run a manual J before any contractor arrived and knew that a 2.5 ton system was plenty. I also know the difference between cutting corners to get it done and doing the job the right way, things that most buyers will have no clue on. I was fortunate to learn from some very good folks.
I called Schuman out of Gatesville, asked if they did work in the Waco area. They came out, I was quiet while they listed what they would like to do and/or correct. They hit everything on my list and their price was very competitive. I was impressed with the quality of the install. (Installation is as important as the equipment.)
Finally, if you can wait until October, you'll likely save money. Every contractor, good or bad, should be pretty busy this time of year and it shows in the pricing. This is when they have to make money to get them through the winter in Central Texas.