hwilson019 ,
To my mind you cant beat a Down sleeping bag. They are much less bulky that synth. They are also more comfortable to sleep in. The down side is that they are expensive and must be keep dry. They are also a pain to clean, but let me assure you that the benefits FAR out way the negatives.
About 10 years ago I purchased a Mountain Equipment Snowline - it is still in regular use. This is a Very warm bag (good down to -9c), It is a great do anything bag, I use it for summer camping, touring and alpine mountaineering. However it is not the smallest of the down bags (pack size 23cm by 30cm) and in summer it sometimes get a little too hot - even when used as a quilt.
Last year My wife purchase a Mountain Equipment Xero 550 this packs a good deal smaller (19cm by 28cm) It is much better in the summer and autumn but it is only good down to about 0c. My wife really feels the cold so if it looking like a cold night she uses a cheapo synth bag on the outside of her Down bag. It works a treat!