The DFI is supposed to be good. The MSI... haven't heard that it's good for overclocking so probably pass on that. The Biostar is good. Mine's running my Opteron 144 at 2.7GHz easy. There's also the EPoX 6100 chipset board which is supposed to be a good overclocker. Also, the Jetway A210GDMS-Pro (or something like that) is good up to 300MHz, though you'll have to use a PCI NIC since the onboard dies when you overclock.
EDIT: Note that Biostar makes two boards, the Tforce6100-939 and the Geforce6100-M9. The "T" version is the killer overclocker. The "G" version can probably overclock, but not as well.