all of those " should" hit close to the same base and boost clocks provided the cooling is up to it, the higher factory clocks usually mean the cooler is a bit better and that have been binned a bit to verify the clocks are stable, but there are many variables like what type of case you are using and such. i would say get the highest clocked one you can. if it drops a little due to heat from a less than optimized airflow in the case then i dont think you will see much difference unless it throttle a lot.