The HVAC repair an sellers of equipment tell me to use a 1" cheapest see through that I can find so as not to put stress on the system, blowers etc. Other experts and common sense say to buy a good pleated high rated merv filter. Any ideas out there as to what to use?

The higher the MERV, the better the filtration. If you have a dusty house, the higher MERV will filter better but also fill up faster. I use a regular MERV 7 and change every 60 days.

That's a great plan MA, and whatever the OP uses the whole key is REGULAR check and replace.