I asked the same question here some time ago and all I ever got from this forum was that the installer is the most important thing. I would really tend to think that this is true with a new furnace. I am not sure how true it is if you are doing a replacement. I asked the pros if any of them had ever used a micrometer to measure the wall thickness of the heat exchangers, since heat exchanger failure would tend to render a furnace irreparable. (Everything else is third party and replaceable) I got no answer. I did get responses that all of the furnaces that a typical homeowner can buy online are of lower quality, and lower grade than dealer only models. I asked about Carrier, which I currently own, and am quite happy with, and some techs said that today they are made like crap. So what I did was download brochures and looked at how they are laid out inside, vis a vis ease of access, ease of changing out parts if needed, general construction, and heat exchanger warranty. I now know which one I am going to buy, and I recommend you do the same. One thing I did find out, which is very disturbing, is that all of them are made exclusively from parts made in other countries, even if they are assembled here. They may be more efficient than the old furnaces, but they sure aren't built as well.
Furnaces have gone the way of everything else in this country. Door hinges are brass plated, not brass anymore, hence the black iron dust near your hinges. Your plumbing fixtures go bad in 5 years, and your door lock sets wear out in about the same. No4 pine is now labeled as No.2, and your bed wears out in three years instead of 12. Roof shingles are rated by the number of years they lie about them lasting instead of by how much they weigh.
We got what we asked for ChiCheeChinkCrap. Now we have to live with it, because all the good stuff is gone forever.
Good summary, and like you said... It all boils down to cheaper/quicker parts and turning them over.
What did you end up going with?
Where I'm located, you have to be a registered 'special' dealer to supply/install Carrier systems therefore I'm wondering if this could be a PIA down the road to get them serviced if necessary. I wouldn't want to trap myself to only a 'Carrier' dealer or service guy and get charged an arm/leg for it.