Heat pump is not a good choice in your area unless it was maybe a geothermal one. A regular air heat pump won't work at -20 and you end up using the electric heater ($$$).
The guy that says he will do a load calculation, did he take any measurements? If not, he probably won't do a load calculation unless you choose him, even then you need to put it in writing. Ask the other guys if they will do a load calculation.
From what you said, you seem to have a leaky house and leaky ducts that are also undersized. Maybe try budgeting for them to fix your ducts at least. Wouldn't make sense to put in a brand new AC and have all that cold air warm up before it gets to your room. I would almost recommend putting wall furnaces and window AC system... you might get more comfort from those if fixing the ducts will be out of your price range.
I would agree that Amana is the best choice of the three. Solid warranty. Just not a big fan of the product myself. I would prefer Trane or American Standard if it was going in my home and the cost difference was not too much.
Originally Posted by SnailRacer
Just my personal opinion.
Thank, everyone, for all your great answers!
Looks like the Amana is going to be the one to pick.
Just one last question - should I get a 2 or a 2.5 ton model?