The Amana Furnace is made by the Goodman Manufacturing company.
When Amana went bankrupt, Goodman bought their furnace manufacturing plant. We install a lot of the Goodman branded furnaces and air conditioners, including installing one in my 85 year old uncles house. It works well for him and our other customers, in the five or so years we have handled the new model furnace I believe we have had two units that had troubles after installation, and those were minor.
The draw back with the brand, imho, is there is no dealer network, you show up with cash at the supply house and suddenly your a heating contractor.
With the major brand equipment, Lennox, Carrier, Bryant, Trane, we have to prove we are a sound company both from a money stand point and a bbb stand point as well.
We have to take manditory training before handling new models, which helps us install the products correctly right out of the box, rather than having call backs.
Get two or three estimates, ask to talk to customers that have used their products, check em out with the BBB, and then go with your gut.
I personally like the 95% two or three stage variable speed drive furnaces, 80% of the time the furnace will run on low fire and low fan speed, meaning for the most part you might never know the furnace is even on!
If you have a two story house, running the fan 24 hours a day, will help even out the temps between the floors and will cost you much less than running your current fan motor year around.
If i can help let me know, this is my 33 year of doing this for a living.