A ton of answers and opinions for your question. I personally have two bags and use them during Colorado archery season. One is a Marmot Helium 15 degree with goose down. The other is a Marmot Trestle and is also a 15 degree but synthetic. The Helium packs smaller and is lighter but there is the concern of it getting wet and losing its insulation value. The Trestle is a little heavier and larger but it has served me well. I once slept in the bed of a truck in Kentucky and woke up with frost all over my bag. That is insulation. The Trestle I think is around 100 on Amazon now and the Helium is maybe 200. I like my goose-down bag but my synthetic gets the most use. Always take a beanie for your head, you will be glad you did.
Enlightened Equipment make some of the best quilts you can get. I prefer a quilt to a full bag because I'm a hot sleeper and it's more comfortable for me without sacrificing anything.
Could be just out of your price range but I'd suggest going with one of the EE quilts and getting it custom for you. I prefer a 30* and can take that down into the 20's with some additional layers. Others may think a 30* is too cold so it's really personal preference.
