Western Mountaineering is all you'll ever need. I also checked out the Mont-Bel stuff which can sometimes be had a for good price. Most important, try to test it out. Get in it. I found they are all cut so differently that you really need to try them.
x2...WM makes a great lightweight warm bag. They are a little pricey but when it is 10 degrees out and you are not cold you won't think anything of it.