This is interested answer from Arc stuff about comparing all above mention packs:
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The Altra 65 would be an excellent choice, although I have noticed that it is larger than the other ones you have looked at, and is not designed for climbing specifically. Since you said you will be doing only a little climbing though, this should not be a problem.
The Axios 50 would work as well, but being a lightweight pack, has less padding on the shoulder straps and frame, so if you were planning on travelling for a month with it, it may be worth considering one of the others for the additional comfort and structure.
The Arrakis 50 weighs 2.2kgs and is heavier than the other packs mentioned. This weight provides additional durability, and it is a very rugged pack. Again though, given that you plan on travelling in weather that is not too extreme, the weather proofing abilities of the pack may be more than necessary, and not worth the extra weight.
The Kata 45 or 37 are on the smaller end of the packs you've looked at, and a 37 litre pack may be slightly too small for a month of travelling (of course, depending on your personal travelling style and how much gear you will need). The Kata 45 may be a great choice for you though and I would encourage you to consider it further. The Kangaroo pocket is a great feature, and is on many of our packs, including the Altra 65 and the Axios 50.