The first rifle I shot was a M16 chambered for 22 LR in basic. They didn't teach you to clean it, they didn't teach you to service it. They handed it to you , you spent some rounds sighting it in, spent some rounds on the target and whomever's post wasn't bent too bad got a medal. (Most folks can read this as AF, LOL)
When I bought my first rifle years later, I really had no preference except for looks and familiarity (later on they taught you about the rifle heh). I went with a AR-15 and had alot of fun. The kick is nothing, it's very accurate and easy to sight in for novices. As time progressed I bought other rifles, pistols and shotguns but the AR will always have a special place in my heart for target shooting.
Downside for newbies having AR's is many "conservative" hunters look at you as a "wanna be" or "wacko" as soon as they see you, no matter your range ettiquette, dress or demeanor. Those preceptions can be changed with interaction, but starting at -5 on a number line is not as good as -0-. I imagine an AK would be worse. At the time I didn't give a crap...hmm, actually I still don't. You might though, heh.
So my vote is AR15. The ammo is cheap and plentiful, the online resources are TOTALLY over the top. If your looking for info and not finding it your monitor is turned off. Also look into a .308 semiauto, like a M14, Robinson Stoner clone, ect. I don't hold AK's in very high regard for accuracy over 200 yards. Sure you can run your truck over them, and if that's your plan perhaps it's an option, but you won't know how accurate you CAN be with a rifle that won't do it's part. Others are bound to disagree with that, but I only have my own experience to judge by.