Yeah, the AMD build is a much better value. People generally prefer Intel either because they don't know any better or for higher end builds. The reason for this is because the FX-8350 performs about the same as an i5 3570K when it comes to gaming, but the FX-8350 pulls ahead in things like video rendering.
At that price point, the FX-8350 is cheaper and a better value, but once you start getting into the Intel Core i7's things start to change. In general, the i7 3770K should perform better than the FX-8350, and the i7 3930K (and anything above that) is going to completely slaughter the FX-8350. This extra performance also comes at a much steeper price, however.
On the other side of the fence, a lot of people prefer Nvidia either because they get caught up in the hype of all the marketing gimmicks (things like PhysX), or because they thing Nvidia is going to be less of a headache than AMD. There are also those who are just Nvidia fanboys, or those who haven't done enough research and just assume Nvidia is superior (Nvidia seems to do a better job at marketing for whatever reason).
A lot of people think AMD cards are a headache because, for the longest time, AMD was putting out rather lack luster drivers in comparison to Nvidia. Nvidia cards were considered more stable because of this, and they'd also usually get a larger performance boost from drivers later down the road. More recently, it seems AMD has finally figured out their driver coding, because current AMD cards have gotten huge performance boosts from new driver releases, which has propelled them ahead of most of Nvidia's offerings. This is a very new development though. Before the 7000 series of cards, AMD drivers were widely considered lack luster and, in many cases, unstable.
Another reason people usually go with Nvidia cards over AMD is because AMD seems to have a worse issue with micro stuttering when put in a Crossfire configuration. I personally can't confirm that, because I've owned both Crossfire and SLI rigs and never really had a problem.
Also, I don't know how this holds true for the current generation of cards, but Nvidia generally does a better job handling filters like Anisotropic filtering, Anti-aliasing, and Tesselation. I have no idea whether or not this still holds true though.
Out of those two builds, though, the AMD build is going to give you a lot more performance. It's also just a decent gaming build as opposed to a super high-end enthusiast super computer.