Wait for NF4.
If you've already got the AGP video card though, I suppose MSI if you want NF3. Dunno how the VIA chipset works, although I've not heard anything bad about it.
There really isn't a good SOLID s939 board that I know of right now, so you'll have to keep shoppin around!
*Edit* Scratch that, Anandtech seemed to love the new Soltek K8TPro-939 board, so you might want to check that out!