Of the 3 contractors selling American Standard furnaces I have contacted, I found George Li of Spring Home the most knowledgeable. He is the only one who recommended to increase the size of the return air duct for maximum efficiency, and that, together with an American Standard programmable thermostat, is included in the installation price.
Installation work went smoothly and they did not leave a mess. I also took the chance to have my aging hot water tank replaced. Their crew accompanied me to Home Depot without extra cost to pick up one.
George Li came back to audit the work of his crew and adjusted the furnace to achieve maximum efficiency (none of the other contractors mentioned they will do that). When I raised my concern that the fresh air intake might be too low for the snow conditions, he agreed to have it corrected, and sure enough, that was done within a couple of days.