I actually don't think that Williams Brewing has a storefront - I called them about 6 months ago to find out and they said no. But maybe they've opened one since then?
Morebeer is fine, really good, even, but Oak Barrel is the easily the best. They have everything, it's relatively affordable, they know what they're talking about, and they even have beer on tap that you can drink for free. I've gotten good advice from the people there.
SF Brewcraft is kind of weird. I go there because it's closest to my house, but I pretty much only buy grain there (sometimes hops or yeast). They're definitely lots more expensive than the other stores, and I've gotten some pretty lousy brewing advice from different people there. Plus Griz (the huge old guy who own the place; always sitting in a chair in the corner) can be difficult to deal with.