It might help to know where your at what fuels is avail i.e. elec, nat gas, propane, wood, etc.  I have had all and prefer natural gas if a choice.  Wood is great if you have a ready supply (exterior furnace).  Heat pumps in the deep south, but I never felt warm with a heat pump.  Brands, I've had carrier and Lenox and both are excellent.  The one I liked the least was fuel oil.  Get an effiecient unit Seer rating if you can.  They pay for themsleves in the long run.  I had wood for a while when I was younger and that was very cost effective.  The new exterior furnaces are clean and work great.  In the midwest, I saw some corn stoves and pelet stoves that were cool, but with the price of corn now, I question if they are still cost effective.  If you use a burning fuel, check the flu!  I had a flu fire once.  Good luck! 

Grand 777, there are numerous considerations ...
- Since this is a new purchase I'm guessing you will stay there awhile. Go with a 90+ efficiency. Depending on your climate and availability go with a modulating 90+. The cost between an 80+ and 90+ may seem high at first. However, if this is an old home the chimney probably doesn't have a liner. In most instances you would need to add a liner in order to install a Code compliant (IRC) induced draft (80+) unit through an older chimney. Once you factor in the cost of a chimney liner, the cost between and 80 & 90 becomes minimal. Go with the 90+. If the house has an old oil burner, DO NOT vent the new unit into an unlined older chimney. NO MATTER WHAT THE CRAPPY TECH TELLS YOU.
- Goodman makes a great furnace, even though it often times doesn't get good CR ratings. Rheem and York are also good units. Buy what is local to your area. That way when it breaks down parts will be readily available. Stay away from Lennox or Amana (pricey, proprietary parts and techs)
- DO NOT install in a damp location. You will have annual repairs if you do.
- electronic air cleaner/purifier/ionizer/etc = if your family is prone to allergies, worth the money; if not pass on these units
- tell your guy to install a proper filter rack and use regular filters and change often.
- humidifier = always a good idea, but I don't know where you are; a good one is 150-200 plus install
- If the existing unit is an old gravity feed, oil burner or conversion job; you will need to redo some of the ductwork in order to maintain proper static pressure throughout the system and get good air distribution. If the house has very large octopus looking ductwork wrapped with weird whitish cloth, DO NOT pull it, breathe it or mess with it in anyway without prior research. Also DO NOT announce that it is there publicly.
- you lose 10-15% efficiency and add that much in utility bills by having bad ductwork and distribution; don't cheap out.
- if you use AC a lot, you may want to add another return or two and especially a high return depending on the house construction, orientation, climate
- if staying for a while, go 16 SEER (R410a) on the AC side; make sure condensate drains are properly and FULLY installed
- you can post further questions here or email me.
Good luck