Phantom 0F/-18C

Phantom 0F is a great bag, I use mine for ski touring so saving weight is nice. What do you anticipate using it for and what temperatures do you plan to be out in?

My summer REI bag, which is 30 degrees (close to yours) doesn't have much fluff either. I've never actually expected the bag to have loft, because there's so little down. My winter bag from Mountain hardware does puff up, but there's probably 3x as much down in there and it's better down. I don't think your problem was the bag unless you left it in a compression sack for an extended period of time. Or just washed it and it's all clumped up. I can sleep out in 5C/40F degrees in the Sierra Nevada no problem with my summer bag, so i'm not sure why you had so many problems with all that clothing on. I will say 3R is pretty low, a good mat helps a lot.

Late to the Party, but the Mountain Hardwear Phantom bags are no longer a good value proposition (not to imply that they were before), but you can get a Western Mountaineering Kodiak MF (Microfiber) for $850 or the Storm Shield Version for $985. The Phantom Windstopper 0 degree starts at $1,100. Western Mountaineering is made in the US and so some of the tariff-related inflation is not hitting them as hard, making them a better value proposition. Not to mention Western Mountaineering makes the best down products in the world. Other folks have mentioned Gryphon Gear. Another awesome option. You may need to wait a while to get one though. Feathered friends is great too but I think Western Mountaineering is amazing. My recommendation, Get a Kodiak MF. The Microfiber fabric may look unassuming at first, but it is incredibly durable, tightly-woven fabric with excellent weather/water resistance and it breathes super well, critical for multi-day winter outings. I have a Puma Storm Shield and while I love the fabric and the fortress feel, a laminate fabric like that takes a long time to pack into a stuff sack. It just traps air like a balloon. The microfiber is a dream fabric. A proper microfiber fabric where the filament count is equal to or higher than the denier of the fabric.

The difference between the Phantom and the Bishop Pass is weight - they're both down bags, but use different fill powers to achieve the same temp ratings at different weights. Phantom -18C weighs 2lbs 10oz and the Bishops Pass -18C weighs 3lbs 2.1oz. Not a huge difference for the price, but if weight is a major concern it could be worthwhile. FWIW I've got the Phantom in -40 (non goretex), -18 and a Ghost Whisperer -9 and they're great bags. My wife has the -29 Lamina and it's fantastic, just heavier and bulkier than the down offerings. I wouldn't hesitate to get the Bishops Pass if it fits your budget and you don't mind the few extra ounces. You can use the extra $$$ to pick out something else on their website.

The Specter used to be called the Phantom Alpine (they are the same thing). Only real difference to the regular phantom is the second zipper so that you can have your arms out when cooking and have more convenience when on a wall climbing.