Does anyone have a suggestion for a good, reliable furnace and air conditioner?

All brands work. It is better to be concerned with the quality of people/company that is going to install it.

Get 4 prices throw the lowest one away and then decide on the company that has been around a long time selling good equipment and warranties. I prefer Rheem and Trane to most any other brands, yes I'm a Rheem dealer and wouldn't have it any other way.