I looked at a ton of moderate to low priced sleeping bags for backpacking, and decided the Kelty Cosmic Down 20 is the best.
All other comparative bags in this price range were synthetic, and did not have the great loft of this bag. These bags are EN rated with Comfort=32F and Lower=21F.
The down is duck down rather than the normally used goose down. I don't know about the merits of duck versus goose, but the fill is 550 rated, is EN tested and rated, and has good loft. I bought around 6 of these bags in different sizes, and 1 did smell a little funky, but I imagine a wash or just hanging it outside would take care of that.
The woman's model should fit to 5' 6". My wife, who is not used to snug mummy bags, found it much more comfortable than the men's short which is specified for the same height. It has a specified fill weight of 21oz and a total weight of 41oz. My actual measured weight is 39oz.
There is a synthetic and down Kelty Cosmic 20, so look closely at what you are buying.
I LOVE my Kelty Cosmic Down 20+ bag. I did a TON of research before purchasing and am very pleased with my decision. I have used it multiple times down into the mid-30's and it stayed very toasty warm. I would have no hesitation using it to the low range of 20 deg and below.
The loft is very nice and cozy. No issues with snagging zippers, although make sure you figure out the adjustment cords at the hood before it gets dark. It stuffs easily into a small bag and could definitely compress even further with a compression sack.