The AK reflects the soviet attitude of "as long as it works". Soviet made equipment has a long history of being rough around the edges, if not down right crude. But the stuff has always gotten the job done. The sole exception might be the Dragonuv, which truly is a marvelous weapon.
The AR reflects the American attitude of "design something revolutionary and then refine it until it works the way we want it to". It also reflects the other American tradition of building multi-function machines and tools. While the AK is pretty difficult to make into anything but a short-range infantry rifle, the AR can be anything from a super short CQB/entry unit to a long range sniper weapon, depending on configuration and caliber. Unfortunately, this kind of versatility means the unit may not perform quite as well in a given situation as some of it's dedicated contemporaries-much like a Gerber multi-plier is not as good as dykes for cutting fence, or a 12" bastard mill for taking down metal, but one man cannot carry with him at all times the number of dedicated tools that a good multi-plier has, even if they don't do the job as well/easily. All in all, though, I (and most) would say that the Stoner design is pretty darn good.
Each culture around the globe tends to display it's attributes and shortcomings in the weapons they produce. The Italians put incredible emphasis on aesthetics, and this is reflected by the definitive "flare" evident in Italian-designed guns.
Germans tend to be a little more blah in the looks department and often surmise that if it works for them, it will work for everyone else. So they over-engineer one platform and come up with nifty ways to market it at a premium price, ignoring any feedback that the unit could benefit from alterations or improvements they didn't think of first (German engineers are definitely primadonnas). You end up with a good product, but one that costs more than a gun of comparable quality from another nation.
The Czechs seem to be somewhere between Soviet and Italian, building guns that are refined and more gracefully styled than the Russian stuff, but generally not up to par in fit and finish with Italian, German and American guns.
Aside from the GP35 and FAL, Belgium just makes really weird stuff
Most other nations seem to just build knock-off's of the aformentioned countries designs.