It's a tie. FX57 is 2.8GHz single core, and FX60 is 2.6GHz dual core. Neither one overclocks very well.
If you are willing to overclock, the Opteron 165 might be better. It is 1.8Ghz stock, but it can go past 3.0Ghz easily, making it faster than the FX57 or FX60. Also, it is dual core, with 1MB L2 Cache per core.