I favor the AR heavily but I have owned and appreciated both.
I favor the AR because it is simply a better gun to me. Better sights, better manual of arms, but I don't go around knocking AK's.
However what I find odd is why so many people say they like both but will favor the AK for a SHTF situation. To me that is generally one of the biggest downfalls right now of the AK platform.
Lets be honest, things fail, even when Glock inscribes PERFECTION of the side of it, they wear, and fail. If you think your AK or any of your guns is magical and will near wear out or fail on you in some way your either not logical, or not shooting it enough.
The problem I see with an AK in a true SHTF situation is if you have to get up and leave, the ammo you are going to be packing is 1) much heavier, 2) generally in short supply even before the craze. Most of the Comm Bloc surplus has been drying up, and AK's are getting harder and harder to find ammo for. (talking the 7.62x39 that is). Also parts are not as common here as the AR platform by a whole ten fold.
If I had to get up and leave, I would want as many rounds as I could take that wouldn't over burden me, but also I want the gun I am most likely to be able to find spare ammo and parts for, generally anywhere in the US this will be the AR platform.
I do LIKE AKs. but for anything serious I favor my AR's. All of them I own at the moment are either BCM or running BCM uppers. If you still think the AR platform is too unreliable I would challenge you to run a BCM with out cleaning it such as SWAT magazine did for their Filthy 14 article where a BCM rack rifle ran more than 14,000 rounds without cleaning. My AR takes the same time to clean as my AK and Saiga 12 do simply because I bring them to work with me and take them apart and toss them in the gun smiths parts washer for a few hours.
The main reason I really prefer the AR is the recoil impulse and the manual of arms for anything serious, even people VERY good with an AK... the AR generally is faster. My BCM with 14.5'' barrel with a mid gas system, compensated, and H2 buffer has a VERY low recoil impulse, so you just hold the dot on the target and squeeze the trigger however many rounds you feel appropriate. The manual of arms is much easier to use, and does not require you to move your trigger hand from the fire control group to rack the action like an AK does. However one slight modification I do find VERY helpful for the $10 I spent on it is the Magpul BAD lever. The T handle is not perfect on the AR with the bolt release being on the left side, however with the BAD lever I never have to worry about it. I can lock the bolt to the rear with never having to remove my hand from the fire control group, I can also do a faster mag change while not having to worry about hitting the "ping pong paddle" on the left side.
I give the AK its credit, but for competition,work, and home defense, I would take an AR before an AK.