Those who want to deal with pet allergens with a home air filtration system will find excellent results with a combination of portable units located in all major rooms of the house, and home filtration accessories for central heating and air conditioning.
Did you know that there are "furnace-mounted" air cleaners, and air duct "grille filters" which can work together to keep pet hair from circulating through the home via your central air conditioning system? This can be a vital part of your allergen control system, as hair and other particles are trapped by the filters and kept out of your air. Portable air cleaners are excellent for controlling the air in a single room, but they can do nothing about the pet hair that gets sucked into the central air conditioning system and blown throughout the home. Consider such "add-on" house air filters when customizing your air; the difference should be quite noticeable.