I agree with MISRy. The Opteron 1212 is your best choice, or if you're budget minded, the 1210. Either can be overclocked to FX-62 performance levels.
X2 4200, 4600 & 5000 = 512Kb L2 Cache per core - fair choice.
X2 4000, 4800, 5200 & FX-62 = 1Mb L2 Cache per core - good choice.
Opteron 1210 thru 1218 = 1Mb L2 Cache per core - best choice.
Opterons are server / workstation class processors, so they're more stringently fabricated, tested, selected and binned for stability, and are yielded from "cleaner" silicon semiconductor material. They operate at lower voltages and temperatures per clock, as compared with their X2 desktop conterparts, which make the Opterons the best overclockers.
Hope this helps, and good luck with you selections.