I am trying to buy a new pack (around...
I am trying to buy a new pack (around 49-60L) will serve me as a backpacking pack, and as a multi-day mountaineering pack...My top considerations are the black diamond mission, and the Ather 60. Does anyone have a recomendation? Or perhaps other great packs that will work.
Both are definitely great packs, you can't lose with those options. Another great pack that I would recommend is the Gregory Baltoro 65. I know it's a little bigger than the range you're considering, but it's a super compressible pack with an excellent suspension system.
I definitely suggest hitting your local outdoor stoor and getting fitted if you haven't before. Happy mountaineering!
I'm really jaded towards Osprey and Arcteryx packs, but all features and comfort considered, the Aether 60 is the one I would go with, especially for your mixed uses. Just remember, pack comfort and function are incredibly subjective, so Thomas is absolutely right, if possible, try them both out before you commit.
As Phil and Thomas said, if it's at all possible get yourself to a store, get fitted, and try them on. That will probably answer your question better than anyone online could. You might also find a 3rd or 4th option that would be even better for your intended use.
For mountaineering use, keep in mind that you'll have extra gear requirements vs regular backpacking, and different packs have different systems in place for handling that gear (external tool attachment points, ways to handle crampons, floating lids that can accomodate a rope underneath, etc)
Personally I think you can find a lighter pack. This is essentially a Cadillac with all its features. If you are carrying under 40 lbs its just too much pack IMO.