Purolator. Some studies I looked at a few years ago indicated that they were among the best paper filter for both flow and filtering properties. Some flow better but filter less, some flow worse but filter slightly better. K&N filters flow well but do not do a good job of filtering small particals at all.
Our 97 Explorer had a K&N when we got it and the intake tube (past the filter) was filthy. I cleaned it several times and dirt always got past the filter. My ranger had purolator filters on it all the time and despite tons of time on dirt/gravel/muddy roads my intake tube was always spotless.
2006 F150 FX4 Super Crew - Bilstien 5100s leveled 2", 35" KM2s, 4.56 gears, Detroit locker, Eaton E-Locker, Traction Bars, AEM intake, Xcal 2
2010 VW Golf TDI 6MT