UltraLite

I own a WM Ultralite. It's a great bag and WM is the benchmark. I also own 2 Gryphon Gear quilts. I think their stuff is very high quality and a great bang for the $$$. They also make bags. Take a look at the Taurus 20\* bag. It's a bargain compared to the Ultralite and it's fully custom so it can be made any width you like.

My western mountaineering ultralite bag. My first one lasted 15 years, a season with the forest service, thousands of miles of backpacking, and countless river trips.

I have the western mountaineering ultra light 20 deg. It’s so good. I can’t recommend it enough. Pricey and worth it!

WM bags are expensive and absolutely worth it. I'll never buy anything else!

A couple of notes on Western 1) their temp ratings are the comfort ratings, not lower limit. 2) the Ultralite is narrower than the Alpinlite, but if you look at comps the Ultralite can generally be considered a standard width. 3) if Megalite is of interest the Sunmerite is the narrower (again standard by industry norms) version.

I like to reference the PCT gear guide for the best backpacking gear, according to PCT thru-hikers: https://www.halfwayanywhere.com/trails/pacific-crest-trail/pct-gear-guide-2024/#sleeping-bags-quilts You'll want to decide between a mummy bag (typical sleeping bag) or a backpacking quilt. Western mountaineering makes arguably the best mummy bags (I have their ultralite and I love it) and the best quilts right now are probably Katabatic or Enlightened Equipment. Quilts have become very popular recently, so it's worth reading up on pros & cons of going that route over a typical sleeping bag.

If you are brand new, get something cheap and on sale. Fair chance that you either will give up backpacking after a few trips or realize that you want to invest more in high-end gear.  You eventually need a quiver if tents, sleeping bags, and packs as no single one is great for all conditions.  For summer, I mainly use: flycreek 2p tent, Western Mountaineering 20 or 40F sleeping bags, and a daypack with side straps that cost about $60 and weighs roughly half a pound. 

I am a cold sleeper too. And I’m embarrassed to admit, I could afford a western mountaineering bag. It was 0°. And I’m 59 and I got the 6 foot six version. Giving me tons of down to snuggle into. I actually use this bag way more than just the winter and I’m always toasty warm.

Western mountaineering. I get cold easily even in the summer in Colorado at high altitudes. I also snow camp

Don’t forget to get a really big bag one that goes way over your head. It’s just so cozy.

It really depends who you are. I can shiver on a Colorado summer night at 11k. So I spent 2lbs on a western mountaineering bag. I love it.