Is the difference in price worth it? Think of it like this, is the price of a GMC Sierra denali at $60K compared to a GMC sierra SLT at $45K worth the difference? They both get you around, but the Denali has more upgrades and comforts. The furnaces you picked all keep you warm but the 96 and 97 have upgrades to provide comfort and convenience.

They're all high effeciency but the difference between 96% and 98% isn't worth a cup of coffee per month, so ignore that. The added cost is in the upgrades of the higher end units, and in the Gas valves and electronics to operate them.

The 95 is a one speed one stage unit with the basic electronic to run it, but almost every thing else is the same as the other two, even the blower motors are the same.

The 96 is a two speed two stage unit with a little more electronics and higher priced gas valve.

The 97 is the keeprite denali, with WIfi and variable heat, (From 40% to 100%, I checked.) with a blower speeds to match, and with some a ION system function for pairing and communicating and whatever..........

As far as noise they'll all be the same because everything is the same except for the gas valves and electronics. and noise will not differ when they're all running full open. But the two with lower speeds will be quieter running in lower speed. If you want to see ALL the specs go here and type in the model number and specifications for document type.

full specifications for all units.

Here is a good comparison for keeprite units.

comparison of keeprite