I had the K&N on my MK5 - hands down the K&N sounded better, Carbonio looks better (especially if you get stage 1&2 pieces) and performance gains are similar with APR getting the edge for better heat protection because it's a CF piece.
I've had the typhoon on mine since 600 miles and love it. In my eyes anything aftermarket is just a filter on a stick. I really should have spent 40 bucks on a filter and piece of pipe from advanced rather than 300 for the k&n, but they both do the job. If you have money to spend definitely get it!
I've used K&N air filters in all of my vehicles over the past 15 years, or so. I put one in my GTI within a few days of buying it, but never noticed any difference in power or sound. Within about a month I had the Carbonio I & II installed and there was a slight difference in performance and a noticeable difference in sound, even before going beyond Stage I when it really became a different ball game.