In order to determine which is the best
ac filter
in your home, you must first establish the purpose of the filter in your ac. Filters are used to keep the equipment clean and reduce maintenance in order to allow for the best airflow. So, the ac filter you use, will be determined by the kind of ac unit you have installed.
The first kind of filters is the standard fiberglass "rock stopper" filter. They are between 2-3'' thick, and are generally used in furnaces, not ac units. The cost of using these filters will probably be one of the highest, due to how often they have to be changed and serviced, and electric bills will be much higher.
Aluminum mesh washable filters are probably the least efficient filters available. They allow dirt and dust to slide off the mesh easily, causing block up in your unit. Many homeowners use them because they don't have to be replaced monthly, but, they are not very effective either.
Polyster filters are 1-2'' thick, and is an upgrade to the fiberglass filter, but still not very efficient. Even if changed regularly, it will still require the ac coil to be pulled and cleaned every 4-5 years. These filters are more expensive than fiberglass, but are also more efficient.
A polyster pleated filter is sold in 1'', 2'', or 4'' thickness, and are more dense, and catch more dust particles. Their efficiency is higher for thicker choices because increased surface area catches more dust, allowing air to pass more easily, in turn your ac is more efficient.
A HEPA filter is generally 4'' thick and offers a much denser material than standard filters. With more pleats, there is not as much restriction of air flow; they need to be replaced every 6 months to 1 year, but unlike traditional filters, the dirtier they get the more efficient they are.
The April-Aire is a high density filter, covering more surface area, requiring fewer changes. It's a good filter with no moving parts, therefore things don't go wrong. Like HEPA filters, the dirtier they get, the more efficient.
There are also electric filters available which are very efficient, but can require service often due to the high voltage used to run them. Although they are efficient, the complications involved, should dissuade buyers from purchase.