Sea to Summit - Ascent AcII

I've used both the Kelty Cosmic Down 20 and the Sea to Summit Ascent series. For the price, the Kelty Cosmic is honestly hard to beat if you’re on a budget. It's warm, decently light, and has held up for me after a few seasons already. The Sea to Summit is nicer overall with better materials and features, but for most backpackers starting out, the Kelty does the job nicely and won't break the bank.

Oh, totally get what you mean about versatility, being able to open it up quilt-style is a game changer on warmer nights. I’ve definitely done the “foot out of the bag” dance too many times before I discovered those features, haha. Have you checked how the zippers hold up over time with the Sea to Summit? That’s one thing I was a bit nervous about, but so far mine’s doing fine.

Quilts, semi rectangular bags (Sea to Summit Trek and Ascent Down) or the Big Agnes Sidewinder series are what you want. The Nemo Spoon series of down bags are also quite roomy. I sleep on my side. I use Hammock Gear Econ Borrows most of the time and I have a Marmot Col -20F bag for anything 20F and below.

Sea to Summit Ascent range. I use one and my mummy bags see little use now

I have a sea to summit backpacking bag that’s 15° rated and once it’s in a stuff sack it’s incredibly small for a 15°. Coleman is basically bottom of the barrel, sleepover style, when it comes to sleeping bags, I’m surprised you aren’t freezing to death at night.

Quilts can get drafts, but then also sleeping bags compress and lose loft as you shift and expose the compressed side. About even in my experience. Sizing, quality of pad straps, or user error are all possibilities if you've had better luck with a bag over the quilt. Also, audio books with a sleep mask headset and ear plugs. Give a pillow a try as well. I use the better sea to summit version and it helped my sleep quality a lot.