I've shot the M-16A2, M-16A3, M-4A2, AK-47, and i own an SKS and an AK-74. If you want affordability, reliability, ease of use, simple maintenance, and firepower, you should go with the AK-47. If you want accuracy, customization, light weight, controllable fire, and have the money you should go with the AR.
When I was doing marksman eval at basic, I used the M-16A2, I shot a 35/50 with 7 jams, I was shooting right handed even when my right eye had horrible vision and I wasn't able to shoot 5 of those 7 jams. When I did my second marksman eval, I used the M-16A3 and shot 38/50 with 1 jam. Again, I was shooting right handed. For my third marksman eval I was shooting the M-4A2 and hit a 68/70 shooting left handed with no malfunctions. Even when we got to let loose on the targets at the end, I ran 5 full mags through it on burst without any problem and put 130 of those rounds in the silhouette at 25m.
On the other hand, I've shot 2 different AK-47s, the owner of one told me that he has never cleaned his since purchase, neither had any malfunctions as expected even when we ran though more than 500 rounds on the dirty one and ~300 on the cleaner one. Since my grandfather gave me the SKS, I've only had a feeder jam once. My AK-74 has operated flawlessly even if I've ran a total of 3 tuna cans(1 tuna can is 1080 rounds) through it. In the shop we've done a price comparison with the AR side of the shop. they were spending $1000+ on their ARs and I spent $800 on my AK. Granted mine is more reliable by its construction alone, but the high end ARs like Adams Arms ARs can be as reliable as AKs, but will run you up to $1600 for the upper alone. My '74 with all the attachments and furniture modification has put to a total of about $1200 which is about the price of a mid-good grade AR.
The reason I would prefer the AK family over the AR is, lets say civilization has melted down and you end up having to survive off the land and protect your area. Cleaning kits aren't readily available and you inevitably end up having to get your rifle dirty. That's where the AK thrives, it's more than easy to maintain and disassemble, you can abuse it beyond any other rifles breaking point and it will still operate, most AK parts that aren't relevant to the round size whether they are from the AK-47 or 74 are interchangeable, and AKs have more variants than ARs, ex. the VEPRs are marksman style AKs.
If you want the accuracy of an AR and the ease and reliability of the AK, do what I did and go for the AK-74. The 5.45x39 may not have the stopping power of the AK-47, but it has the perks of both ARs and AKs. Plus the 5.45x39 has slightly better ballistics than the .223. Since I've bought my '74, I've never felt like I didn't get my moneys worth out of it.
I've shot all three type rifles and own 2 of those types.