Just curious on others opinions on this, its one of my next gear purchases. so ill set the question up like this best bag for under $200 ? best bag between 200 and 300 ? and best bag above $300 ? overall weight will also be a factor thanks to all
I don't know if this will be much help or not but here's my $.02. Bags aren't something that get recycled much by me anyway. I still have a +35 north face cats meow from about 20 years ago. Besides that here's my line up: I havean REI rated for -10. I've camped in it in December and never been cold... cost was 299$, it's heavy tho. I have a 0 degree montbell, 10, 20, & 30 degree bags that are also REI brand. I also have a badlands (I think is rated for) 15 or 20. The badlands was cheaper (-200$) and seems to be a good value although it's my most recent purchase. The rei brand bags I've had excellent luck with, I'm not sure if they make their own or if it's sub'd out but they've been really good for the $$. That said my montbell is probably my most "impressive" bag. For being as light as it is it's still very warm. It's has only a 10 degree warmer rating than my -10 but is milestones lighter than even some of my +0 bags. It came at a higher price though... if you're looking for best overall value REI bags have given me nothing to complain about.
I broke down and bought a Western Mountaineering 15 degree bag a few years ago. It's changed the way I backpack hunt. Between that and my Big Agnes tent I've reduced weight and bulk in my pack significantly. A good down bag should last a long time if you take care of it. It cost me $350.
I bought the Kuiu 15 degree bag last year. If I were going to buy a 0 degree bag, I would not hesitate to buy the kuiu bag. I know a lot of people question the "waterproof down" and the DWR, but I've had great luck with mine. Packs down small and is very light. Water beads up on the exterior if you get it wet, dries quick. If you can wait for one of their 25% off sales you can get them for a pretty good price relative to some other brands. Just my 2 cents.
Best bag...best is probably dependent on your application. If you plan on just bivy hunting and crashing under a fly, you may want to sacrifice some weight for increased water resistance and fill. I always stay in a lightweight tent, so my 0 degree Mountain Hardware Phantom has been amazing. It's super light and warm, but I know it doesn't repel external moisture well.