I've recently picked up a 55 litre
Arc'teryz Khazri 55, it hasn't been used a whole lot yet, other than one two day trip, but I carried it about 40km through some pretty thick bush in the pouring rain. It was extremely comfortable and felt already "broken in" (aluminium stays are definitely the only way to go). I wouldn't hesitate to recommend Arc'teryx to anyone looking for a well constructed, comfortable pack. This is from their less expensive line made in the Philippines (quality is still high), their standard more expensive line is made in Canada.
My larger pack that I've had for must be 18 years or more is a MEC North Twin, about 100 litres. I've taken this on hiking trips of up to two weeks. They don't make this model any more, but it is very similar to the
Alpinelite model below. The North Twin is a simple top-loader with lots of space, one large main compartment, and a smaller flap compartment. The Alpinelite model has a full length zipper (I'm not a fan of these zippers, one more thing to break).
The MEC gear is built to last, comfortable, and reasonably priced, and MEC has a great warranty.
For a day pack, I've have a Spec Ops T.H.E. pack. It's not all that comfortable to carry, mainly because it doesn't have an internal frame. I am going to order the plastic frame insert for it and that should make a big difference. It is certainly well constructed. My only other complaint about this pack is that the chest strap when done up is at about my throat level level which is no good.
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