The Choices in the 1 inch variety are normally:

Standard Fiberglass Throwaway Filter - these are filters from the 1950's that are designed to remove only the larger particles from the air and, in industry-designed testing, do not do that very well. They are only 3-5% efficient at removing 10 micron particles and larger from the air. These filters do have a very low resistance to the flow of air and, for this reason, are the filters most often sold for home units.

Polyester Throwaway Filter - these filters are 10-15% efficient, and are a higher quality filter than the standard fiberglass throwaways. These can be used when better filtration is required or desired.

Pleated Filters - these filters achieve more filter surface area by folding the media into a 1 inch frame and can use a higher efficiency media without adversely effecting the resistance to flow. - to a point.

Others - any filter that does not fall into the above two categories (metals, plastics, cellulose, electronics, etc.).

In today's marketplace, higher efficiency filters are available at most retail home stores and homeowners need to be aware that some of these filters (usually in the MERV 11 and higher category) may create low airflow problems in their system. In most cases polyester disposable and pleated filters work the best in homes.