JP Magazine did a test and write up on them sometime ago - it turns out there were some big differences between the different intakes. This info is from jpmagazine.com
 
 
Stock Jeep
Install 1-10: 10 (bolted on just like stock)
Filtering Element: paper and foam
Average Peak Torque:188 lb-ft
Average Peak Horsepower:142.3 hp
Pros: 
installs great 
filters really well 
high resistance to water intrusion into engine 
Cons:
paper element falls apart when wet 
doesn't flow that well 
it is a stock part.
 
 
 
Mopar intake
Msrp: $359.00
Install 1-10: 8
Filtering Element: Cotton Gauze
Average Peak Torque: 199.8 Lb-Ft
Average Peak Horsepower: 155.6 Hp
Pros: 
Well-thought-out kit, with all the parts needed, and then some 
Has factory backing. No more possibility of warranty denials thanks to intake kit. 
Can get parts for it, as well as oil and cleaning kit at 
dealers nationwide
Cons: 
With the throttle body spacer, it can be more difficult to install than others 
Same issue with cold air separation as the aEM kit (large space at the area behind the filter near the under hood fuse block) 
Included hose clamp doesn't fit pCV hose at the intake tube
 
 
 
Airaid intake
Msrp: $399.82
Install 1-10: 6
Filtering Element: Cotton Gauze
Average Peak Torque: 200.9 Lb-Ft
Average Peak Horsepower: 154.0 Hp
Pros:
Gradual taper on intake tube 
Good power numbers 
unique design has filter bolting to coldair mount on one side, and tube to the other. Tube doesn't actually bolt to filter.
Cons: 
Child-sized screws for cold-air housing 
requires removal of valve cover bolt for a brace 
requires removal of underhood fuse block, fuse block bolt, radiator bolt-in rust areas, this could be a problem.
 
 
AEM
Msrp: $362.71
Install 1-10: 8
Filtering Element: Synthetic Dry filter
Average Peak Torque: 198.4 Lb-Ft
Average Peak Horsepower: 155.1 Hp
Pros:
no oiling needed-easy cleaning in a bucket of water or smacking on a bumper 
among the best filtration of aftermarket conical filters 
all parts needed for install were included, with extras to boot
Cons:
With the throttle body spacer, it can be more difficult to install than some others 
halfhearted attempt at separating ambient engine air from the intake (the area between the under hood fuse box and the filter is largely open 
we'd stain the bright-white filter on the first 
off road trip we took.
 
 
The Mopar, Airaid and AEF were the best. If I were going to buy one, it would probably be the Mopar.