Use the filter that makes sense for your circumstances.
I cannot live with a el cheapo blue fiberglass filter, whether it cost
$0.57 or $1.29 I am mold spore sensitive and these simply do not trap
enough dust and mold to keep my body peaceful.
At a minimum, I want a Merv 8 pleated filter. Yes, they place an
additional load on the fan. However, the filter frame in my unit was
changed out from a 16x20 to a 20x25 to partially compensate.
Additionally, pleated media filters are available in 4 inch depths to
fit inside standard filter frames. Honeywell filters use this media.
You won't find these in stores, you'll have to find a Honeywell dealer
to buy them from, or find them online. These are also Merv 8 and Merv
10 filters. A 4 inch deep pleated filter will come close to the fan
loading of a el cheapo fiberglass filter, especially in the first 30
days. When you change them out, every 90-180 days, htey will be HEAVY
with all the dirt collected.