re: HVAC unit replacement

You can read my thoughts on this, as well as others, in this thread on page 6 LINK and your service tech is correct that the quality, experience and attention to detail of the installers is more important than the equipment manufacturer/name brand.

Best available - well I assume he is likely referring to more expensive and complex multistage VFD units, numerous pros and cons to those, but there is also many positives to applying the KISS principle with basic, less expensive/complex HVACs.