I'm not sure about the absolute best (is there such a thing?), but I have an Asus P4P800 Deluxe that I have been very pleased with. It performs well, is extremely stable, and yes it does have onboard sound. Plus, it is a pretty popular motherboard, so there are a lot of people that can answer questions about it. I personally tend to stick with Asus motherboards, although I have heard a lot of good things about Abit and have had a positve experience with a Gigabyte. Due to previous negative experiences with ECS and FIC, I stay away from their stuff.