Robert,
Am Std and Trane are very similar. The furnaces I believe are identical, but their condensers are different. I like the Trane line........I can sell anything and choose Trane and Ruud. I used to like Carrier alot until "Puron" came out and I started installing them, I had to go back and install factory fixes on most of them, mostly for noise. I went back to Trane after that. I have an XL16i and a XL19i at my own. I put in an XL1800 Hp at my sisters, 2 XL16i's at my brothers, and Trane at all of my friends houses and
90% of my customers. I wouldn't install something that wasn't going to make me go out and fix it regularly. All of my customers do Preventive MAintenance and most of them have 10 year Parts and Labor Warranties form Trane, actually Am Stnd.
They are not over engineered, they engineered to last. Trane used the Recip compressor for ever, but they manufactured it and it was the quietist, most reliable, and easiest service, unless you are climbing into a 5 Ton XL19i, then it is like being in a small house! The higher end companies (better trained, longevity intact, price for profit and stability, do load calcs ON EVERY INSTALL, install IAQ devices to increase your comfort and your health................), are the ones you see using higher end equipment. Low ballers use the lesser brands of equipment.
Have the company check your duct system (stretches forte'), load calcs, several options of efficency, several options of IAQ products.
Do not go crazy getting too many contractors. Go look at some of your friends homes that have the equipment you like. If they are totally pleased and would have them do it again, call that contractor. If they said they had the best price, call another company. DO NOT SHOP ON PRICE. You are making a 20 year investment, not a one time layout of a bunch of money. Weigh the value of a comfort system rather than have a new heater installed, hopefully AC too. If it is over 10 years old get that done when you are getting your furnace installed. Get 2 maybe 3 proposals. Visit the references that they give you and inspect their work. Were they clean, did they get what they were promised, was the company responsive to their needs.
OH HELL, I am on a soap box......................................jumped off.......................I'm done. Any more questions you really want me to talk about I would be happy to discuss with you.
Good Luck
By the way you can't go wrong with either one. Make sure you get 2 stage variable.