Ive had both....I dont think one is any better than the other. They make a few different models...some flow more than others but are less protective. Dont get the BMC track filter if you are riding street alot. Just get the BMC race. Also you will need to remap (power commander)the old girl if you get the Race or Track filter. So either way you will be happy. I just changed to the BMC because my K&N got ruined because i sprayed the wrong cleaner on it and it f'd up the element. You wont notice a difference between the 2. Just my 2 cents!
I've got a K&N on my R6 and a BMC on my Honda. I like both of them to be honest. You can get the K&N cleaner at Autozone or Advanced. I don't know where to get the cleaner for the BMC, but I'm sure you can find it online.