Homeowners often shop for their first replacement HVAC system by investigating and choosing among various equipment manufacturers, then trying to find someone who will install it cheaply. But they have the cart before the horse.
An HVAC system is only as good as the installation. If your chosen brand is installed by a poorly trained or a sloppy technician, your system will probably fail years ahead of its time; airflow may be inadequate; dehumidification may be unsatisfactory; you may have drafts; you might have to dust and vacuum more often; you might have mold problems; and you will have a higher energy bill. It's like buying a nice car and putting sugar in the gas tank.
But if you choose a dealer/installer who does good work, even though he prefers Brand B or Brand C, you will be much happier with the results. Brand B or Brand C might not have the same reputation, but equipment quality is more about perception and advertising than it is about design and manufacturing. And equipment performance is heavily dependent on the ability of the dealer and the installer to design your system and to configure it properly.
Some manufacturers are very careful about who they will authorize to be dealers of their equipment. Their brands usually have better reputations and better track records than manufacturers who are less choosy. These are often the very brands that have the best ratings in Consumer Reports.
If you went to the best installer in town and had him put in the cheapest equipment he could get, you would be far better off than if you chose the best equipment and then looked for a cheap installer.
CRUD = Contamination Resulting in Undesirable Deposits.
CRAPP = Contamination Resulting in Additional Partial Pressure.
Change your vacuum pump oil now.
Test. Testing, 1,2,3.