+1 on Marmot
+1 on Mountain Hardwear

As always, do some research. There are a lot of good websites with reviews, discussions, etc. out there. The type of use you want the bag for is very important:
-Dry climate vs. wet?
-Compressable or bulk not that big of a deal?
-Light weight needed (personal carry) or weight OK (vehicle carry)
-wide temp ranges
-Use with second person (zip together?)
-Hasty camps (tactical) vs. deliberate camps (backpacking, camping, etc.)
-High visability (blaze orange) vs. concealed (camo)
Those are just a few things to consider. I'm sure you can think of other issues/considerations that are particular to your situation.

And, generally do go with a bag with a rating higher than you think you need. You'll a) get a margin of safety and b) compensate for the manufacturer's overly optimistic claims.

HJ