Not trying to start any brand arguments but are these from the same installer and brand? How are the warranties between the two and not just for the units but on the installer for labor? Have you seen any of the work that they've done before see if they do a great job on the duct work and other important details?
The rates can vary a lot.
When I did my shopping, I followed the advice of my friends and got three bids from three different installers. After setting up appointments, I watched YouTube videos and online reviews for the particular units I was considering to see how the reputation was for entry level versus premium versions within that brand to see you with the pluses and minuses were. I checked 3 installers the cheapest one was around $6500 for a Rheem 80%furnance 75000BTU, and 13seer single stage A/C with a one year labor warranty (I don't remember the factory warranty on parts). We had worked with them for maintenance and they always had a different technician and they either had the older unit blow too hard or too gentle on the igniter, so I decided against them.
The second one was the one who won with a five year labor warranty, a 14 vs. 13 SEER, the reviews I read on American standard (Trane) seemed to fit my liking, the employees seemed much happier and had been there a while.
The third one was selling the same unit as the first one for about $9,500. They were professional but they just seemed overpriced and they kept trying to upsell me to the most expensive machine possible at a tune of $20, 000. But the entry level I think they only offered two years of labor warranty with the factory warranty on the parts.
The company that I went with I am very pleased with so far. They did a better job than the original company that was maintaining the old unit. A friend of mine went with the third company and his results haven't been Stellar has he had to figure out a drainage problem himself after the install.
Sometimes what you pay for is what you get but some times paying more doesn't guarantee you're going to get a better service.
The unit I chose had the problems I could live with. The Trane / American standard air conditioners have a unique coil design that has to be maintained correctly and the furnace is louder than most. To make sure it was done right I'm having the installer who's a certified dealer maintain it for me. I can live with the louder noise as it does a much better job and it doesn't sound like it's about to blow the whole house up when it ignites unlike the old Lennox it replaced.
I decided against the rheem as the reputation was not quite as strong for entry-level models at least at that time. I wasn't going to give Lennox another chance after having two failed heat exchangers over a span of 10 years, A series of igniter problems that were never resolved entirely, and the problems with our rental house with its Lennox, and the reviews at that time did not inspire confidence either. Your results may vary and you should do some additional research on the different brands on the efficiency and feature level that you're considering buying to see what their current reputation is for that segment compared to others. You should research the warranty of the units, the installer, the reputation of the installer, and from there hope and pray you make the best decision.