I don't think you'll get a majority vote on this one. Everyone has their reasons for choosing what they bought. You're better off starting a thread asking why people chose the CAI they have.
I got the K&N
FIPK because it puts the filter in the engine bay, within clear view. I don't want to crawl on my back and look up a fender to see if the filter needs cleaning. Screw that 50,000 mile cleaning interval or whatever the manufacturer recommends. I clean it when it looks like it needs cleaning, no matter how many miles it has been since the last cleaning.
You'll hear arguments about cooler air in the fender vs. hot air in the engine bay. Straight shot vs. bends in the tube. I don't know. All the magazine reviews I've seen I think claim under 10 rwhp, so the difference between each CAI has to be in the 0-5 rwhp range. To me, it's not worth a whole lot so I went with what looked nice and what was easy to get to.