I am partial to Lennox. We primarily do work on very high end homes, and commercial new construction. For us, we have to be associated with the very best that is available.
I would agree to this statement though, I would much rather have the cheapest furnace on the market that is installed 100% correctly than the best furnace out there installed incorrectly. Installation has more to do with how noisy, efficient and reliable a piece of equipment is.
Ruum/Rheem, IMO looks like it was designed by the Feds 50 years ago, its not aesthetically pleasing at all, and, on paper, they don't compete with the Big three (Carrier/Bryant, Lennox, and Trane). If you want the best of the best, it doesn't take more than 5 minutes visiting the equipment websites who has the quietest, more efficient equipment available. To boot the representation of Rudd/Rheem isn't the greatest, and they don't care who they sell to, which has really degraded their perceived quality (bad installations rub off on them).
For 12 years, I was a Trane dealer, and held on through some very bad local drama/politics. I still believe that the best A/C units out there (fit and finish, internal quality) is the Trane unit, even though I don't sell them anymore, it wasn't worth dealing with supply chain issues, warranty follow through, and most importantly, local technical support. I know now that Ingersol Rand now owns them, and they have had some quality issues since then, but cant comment on it because its nothing I have had personal experience with.
The local Trane branch (Trane owned/operated) had some major issues taking care of us, and Trane National was horrible in both response time, and technician competence.
I deal with those exact same issues with local distributors that are 3rd party to their equipment brands. Here locally, there is a Goodman owned branch, and the Rest of the brands are locally represented by a 3rd party. 3rd party representation for the most part, from my experience is a complete joke.
Lennox is the ONLY company who decided that they would only have one client: The heating contractor. No 3rd party vendors. Their support is flawless. You dial 18004Lennox, and you have access to the Best Minds in the HVAC industry, from applications, to tech support. That is huge for us with our business focusing mostly on cutting edge system designs and equipment.
Lennox has the most comprehensive product line that I have seen, featuring Integrated Variable Air Flow Zoning, Several options for Air filtration, HRV's, Residential Economizers, humidification, hot water furnaces, heat pumps, dual fuel setups and on and on.
If I wasn't a Lennox dealer, I would definately be with Carrier. The main reason is for their Infinity zoning system. Its something that works very well, and IMO, is the only other one to consider out there other than the Lennox Harmony III system.
ANY HVAC contractor can get parts from Lennox, and have an account with them. They may not have access to the full equipment line, but they can get parts. As far as home owners not being able to get parts, I believe in that systems. For the DIY's out there, you need to get a good relationship with a local HVAC contractor.
For the true DIY'er that wants to completely save money, and do everything himself, Goodman is a great option, because you can get it all over the place, and people aren't ashamed to sell it to anyone. You get exactly what you deserve. If you do a 90% plus furnace, you will be screaming and yelling wondering how any heating contractor deals with the condensate trap installation. My main Beef with their product line now, is that their furnaces are still 40" tall (Trane also, they are behind the 8 ball). With the taller high efficiency coils, it makes proper installations difficult, especially with air flows over 1500 cfm that require dual intakes.
Now that Daikin owns goodman, it will be interesting how things change.
If anyone needs help getting their hands on anything, let me know, I can help. I am licensed in most every state here in the West, and also have family with their own businesses out in Hawaii and other states.
This is a great forum, it has helped me a lot with my projects, and would love to contribute anything I can on this topic.