Here's a link to my experience with the MSI 975x Platinum V2.1 board and an E6300:
MSI 975X + E6300
Also, here are two links over at Xtremesystems dedicated solely to the Gigabyte and MSI boards:
MSI 975X Platinum
Gigabyte DS3
Gigabyte also has 2 other popular 965 based boards...The DS4 and DQ6, but the DS3 seems to be the most popular with the E6300/E6400 crowd.
Now, the MSI is using the 975 chipset and the Gigabyte is using the 965 chipset so you'll have to figure out what you're looking for. If you want Crossfire capability, your best bet is the 975 chipset...Just be aware that it doesn't overclock as well as the 965 chipset on the E6300 and E6400 conroe.
On a final note, I know that MSI will be releasing a 965 chipset board called the 965 platinum...They currently have a 965 board (The 965 NEO F I believe), but I haven't heard many good things about it.