The great thing about an SKS is that they were generally put together by people that know how they should be put together. The drunken monkeys at Century as far as I know, have never put together an SKS. Right now, I have 3, a Russian, Yugo and a Norinco. I would say the Russian is the best finish, the Yugo has some pretty neat (albeit useless) features like the grenade launcher, sights and night sights, and the Norinco is a bit more sleek with it's spike bayonet rather than the blade bayonets of the other models. My Chinese SKS does have the pinned barrel rather than the threaded barrel of the European design but I really haven't seen that as being a problem.
They are all built like tanks and having been designed from a scaled down PTRS41 anti-tank rifle, really are over-built for the M43 cartridge. As far as problems go, because a lot of them come covered in cosmoline, you really need to get in there and get that stuff out, especially in the chambers, firing pin channel and gas tube. If you don't get it out of the chambers, you are looking at failures to extract. If you don't get it all out of the firing pin channel, you may have a slam fire. If you don't get it out of the gas tube, now you can have short stroking problems. Once you have them cleaned out though, in most cases, they are VERY reliable and rugged. The only problems I generally hear about concern the 59/66 and 59/66A1 Yugo rifles. Some of the rougher condition rifles may have corroded gas valves that can lead to undergassing problems so if you go the Yugo route, make sure the gas valve is in good condition. Other problems tend to pop up when you try to bubba them and make them into something else. Aftermarket magazines tend to leave a lot of folks with feeding problems so I would stick with the issue factory 10 round fixed magazine and use the stripper clips they were designed for.
Now when it comes to AKs, there is a pretty wide variety out there ranging from excellent quality like Saiga and Arsenal brands all the way to drunken monkey rifles sold by Century. It's all going to depend on who you got your rifle from and what kind of quality went into its construction. Keep in mind, higher quality tends to mean high prices as well. Then there is the milled receivers of the original AK-47 or the stamped receivers of the AKM to decide on. Milled tends to be more accurate but stamped tends to be lighter in weight. Then there is the caliber. Do you want the original 7.62 round, the lighter 5.45mm round of the AK-74 or a 5.56mm version? Do you want a folding stock (decide between underfolding or side folding since there is both out there) or a fixed stock and when it comes to stocks, do you want that in plastic or wood? Like I said, a LOT of choices out there.
Now the one thing that the AK has over the SKS is firepower. 30 round mags are standard but then there are also 40 round mags as well as 75 round drums to be had as well. The trade-off is that the controls of the AK tend to be not nearly as ergonomic as the SKS and the accuracy of the AK tends to be a bit looser than the SKS as well with all things being equal.
Really, the best thing to do is just to break down and get both designs. Hell, I couldn't make up my mind which I like better so I have samples of both weapon types but I think if it were me looking for the better accuracy I would go with the SKS but if I wanted to burn lots of ammo, it would be the AK.
). They're also generally cheap, the most quoted price I hear for these rifles is about $300. 
