A client I do work for is a mechanical contractor that basically can get equipment from every manufacturer. Both of the managers in service/parts told me they put Janitrol in their homes. Best bang for the buck according to them. When I was getting estimates from local contractors of whom mainly sold one brand, I asked their opinion and they lambasted them as garbage as expected. I couldn't have my client put in the system because they are several hours away which is difficult for service obviously. I went with a Trane from a local dealer. It had several initial problems mainly a condensation hose was kinked and causing stuff to screw up. Once that was figured out it has worked flawlessly over the last two years.
According to them, most all of the brands are built to similar standards. A big chunk of it is cost and how the company markets them. They said none are junk per say, but all have somewhat cheap construction/parts. I guess I trust them the most because they probably install 10X as many systems than any of the small/local type shops and they certainly have nothing to gain by selling me equipment at cost. They said if I was getting the furnace local to go with whoever has the best combo of price and service as they felt the brands were pretty much equal. Interesting though as my estimates ranged from $2000 to $4500 for basically the same thing. $4500 was Sears who I called just to see what kind of scam they were up to. Very high pressure and really pushing a 12 month no interest/no payment plan. $1000 higher than the next highest estimate is more than enough to cover their interest cost for the year! I believe Sears unit is a trane as well, but they might change monthly so who knows.
It's very hard to get a very good unbiased opinion on this.