Originally Posted by kickstand
Based on this I would go with one of the 60,000 BTU units. At 864 sq feet you probably need more than 45k btu's.
There are plenty of calculators out there you can google. I just did a quick one at 864 sq feet with 8 foot ceilings and normal insulation in our area's weather factored in and it called for 50K+ some change.
Between the Bryant and the Carrier I would now purchase the customer service of the local HVAC install place. I wouldn't worry too much about the brand. Though I would compare the warranties.
I thought you were a wood stove guy.