typically if you ride dusty trails or wet muddy trails you should go with a good foam filter like a uni. If you ride more dunes or where dust and mud aren't an issue then a k&n would work.
If you riding on red Dirt/Clay from GA, You Definitely want a good 2-stage foam filter. The dust would go right through a K&N and you would end up having dirt baked on top your piston. Been there done that no fun
I'm using a 2-Stage UNI and have had great luck with it so far but haven't ridden in much dust yet. Keep it well oiled and you should have no problems.