Need Furnace Advice

[crappiewisdom]

I just had my furnace checked for the winter season. The guy said my secondary heat exchanger is bad. The furnace is 16 years old so I am thinking it would be best to replace the whole furnace. Am I right?

Any thoughts on what are the better brands or are they all about the same? The air conditioning unit is the same age. Should I replace both at the same time?

What else do I need to be considering, besides the reputation of the installers?

Thanks!

I now realize this should have gone to the "off topic" section but I don't know how to move it.