4670K vs FX 8350?

the 4670 will be faster at most computing tasks and most games in the past 2/3 years.
However, more games are being created to make use of up to 8 cores, instead of just 2 or 4cores as the case the last few years.

so anything that has support for up to 8 cores like watchdogs, BF4, few others... 8320 better
 
Overall, the 4670K is better, the fx 8350 may be more powerful in some areas, but it uses way more power and therefore produces way more heat. I really like the CPU boss site. Here is a link that will give you a much more detailed comparison of both processors from which you can make a much more educated decision.

http://cpuboss.com/cpus/Intel-Core-i5-4670K-vs-AMD-FX-8350

P.S. I noticed you were asking about the 4670k not the 4670, so i revised my answer