If you want a bullet hose, get an AK. If you want a cheap, accurate semi that can be converted to a bullet hose, get an sks. Both can be "fixed" to shoot FA.
(1) All post-1986 civilian semiautos, including civilian AK's, must be designed to be difficult to convert to full auto, or else they
are considered full auto for the purposes of the National Firearms Act as amended by the McClure-Volkmer Act, even if not actually converted.
(2) With comparable ammunition, sights, and shooting technique, AK's are just as accurate as SKS's. We have a pristine 1952 Tula SKS and a Romanian AK in our household, and they shoot comparably.
If you don't care about detachable magazines and don't ever want to mount optics, go with the SKS. If you want detachable mags or might want to mount a scope, get an AK. Otherwise they are comparable, except the AK is a little more tolerant of dirt and lack of lubrication.
AK's are popular around the world because most wielders went to the "Insha'Allah" school of marksmanship*, which is, frankly, unAmerican.
When TSHTF or TEOTWAWKI, you would want to conserve ammo, not bullet-hose it down range. While there are recipes on the internets to make black powder, I've not seen anything about making your own cordite. In the aforementioned "hell" scenarios, measuring twice and cutting once would be in order over the hail of lead.
The AK is a 300-yard rifle. Any target you can hit with an SKS, you can hit with an AK, and they fire at exactly the same rate. Once and only once when the trigger is pulled.
The fact that full-auto AK's are sometimes used by irregular forces untrained in marksmanship does not mean that the platform is made to be used that way, or is not capable of being used any other way, or that civilian AK derivatives would/could be employed the same way. And those you speak of would shoot an M16 no differently.
The AK is popular around the world because the Soviet Union provided millions of them to its proxies free of charge, because it is easily manufactured with relatively low-tech equipment (unlike M16's and such), and because of its RELIABILITY even when abused. Non-automatic civilian derivatives are popular with U.S. shooters because they are reliable, they are chambered for a versatile and economical cartridge, they look cool, they are fun to shoot, and they are a great value.