I would appreciate any and all reccomendations as to new gas furnaces. Are any
of the usual brands (Carrier, Rheem, Trane, Lennox etc) any better, worse,
cheaper or more expensive than the others? Thanks in advance.

The installer is the most important part not any hack can do it right.
Get a load calc in writing. If you want a Variable speed blower or a
humidistat- thermostat look at Carrier or Lennox. 10 yr warrantys a must
with the fancier equipment .