The best furnace filter options are the disposable pleated and disposable electrostatic filters, according to Bob Vila. The Family Handyman also lists disposable pleated filters with a MERV rating of 7 or 8 as a good compromise between efficiency and cost.
Disposable pleated filters remove small particles, which helps allergy sufferers, and they remain relatively inexpensive. MERV ratings are usually between 6 and 8 and the filters are made from polyester or cotton paper.
Disposable electrostatic filters have a MERV rating of 10 and are particularly good for households with pets. The primary cons of this type are expensive custom sizes and higher total cost if replaced regularly.