Im no sifu, but from what I understand KnN uses some kind of oil to trap dirt on its I think fiber-based filter. Good performance and flow but needs to be re-oiled, and some say after long periods of usage the oil gets sucked into the engine and decreases its performance.
Apexi (open pod) is a dry-mesh type that is highly effective and clean, Im using this one. The entire filter needs to be changed once worn out. Blitz uses washable metal mesh which gives good performance and induction noise but bad filtering quality, same for HKS with their foam-based filters, but for HKS you need to replace the foam once it gets worn out.
Other filters, dunno. :) But I generally avoid foam based filters as they rupture after some time and tiny bits and pieces gets sucked into the engine. Sifus correct me if Im wrong...
My 2 Sen. BTW you might want to check out Racecraft CF Airfilters, if your car is suitable for usage. Currently Protons with Mitsu MAF sensors cannot use unless a custom intake is made (Will cost a bomb).