The newer bi-polar ionizers are gaining in popularity. They are based on NASA tested air cleaning technology. The HEPA filter system is a good one, but expensive to put in and maintain. Expensive to put in because of size and constant power consumption. The good ones require their own circulation motor so as not to over tax the furnace motor to pull air through the 4 stacked filters. The filters are expensive as well, but for someone with serious allergies they are probably the best.
Since we put ours in I have noticed that our air filter is dirtier each month, but the amount of dusting I have to do has gone down. The dirtier filter doesn't bother me as our HVAC professional advised when we put the new system in to not get suckered into buying the expensive "cleans all" filters. The explanation was simple. Those filters are much denser to catch the much smaller particles which requires the motor to work harder to pull air through them.
What we were advised was to use the basic cheap filters, the buck to buck fifty kind that are pleated and have the metal screen on one side, and to religiously change the filter every month. We do on the first day of the month every month. The HVAC people have also advised that our heating/cooling exchanger, we have a heat pump, seems to be cleaner. The come every 6 months to clean and check the system before the heating or cooling season begins.