If you are aquainted with overclocking, then get the 1333mhz, if you want to get aquainted go with the 1600mhz. Also if you want to just set it to the standard go forthe 1600mhz. However, there has been proof that faster ram is not always better, but generally the 1600 mhz models are made bettter, with better timings also. Timings are more important than mhz speed.
If you have tight timings and its set to 1333mhz, it theoretically would be faster than 1600mhz memory with looser timings.