From what I have heard, Ruud is a decent brand. They are a slightly lower priced version of Rheem. Rheem bought them a while back and I think they are largely similar and Rheem is a top notch brand. More important than the actual brand name is the quality of the install and the service and support of the installing company. You should get some references and actually call them to see how their past installs worked 1,2,or 3 or more years after the fact. If they didn't do a "manual J" heat loss calculation then I would highly recommend going to http://www.hvaccomputer.com and purchasing their software for $39 (homeowner one use). This will allow you to spend a few hours with a tape measure and then enter the room by room measurements into the program and you will end up sizing the equipment and ducts and fan etc. correctly. If the contractor did a manual j calculation then he should be able to supply it to you to show that he isn't doing a "rule of thumb" sizing for the furnace, fan and ducts.