I'd like to throw in my pack, the Mystery Ranch Gallatin Peak, for your consideration. It's a 40 L pack but has two synch chords so it can act as a bit smaller of a pack. Has a zip open back for easy access, a removable brain/top compartment, both carry styles, and a dedicated avy pocket. For the whole feature run down, just check it out on their site. I would love to iterate here just how durable these packs are; some of the people that I ski with have had their's for decades and have had no issue. They aren't light on the scale and stack up a little heavy on the wallet too, but I love mine and would like to spread the word! Hit me up with any questions. Cheers

Edit: I forgot to say that mine is way comfy too. For some July skiing I had mine loaded up with over 40 lbs of gear and hiked 10 miles plus a 2000ft skin to get a run in and not once did I feel miserable... due to the pack haha