Never mind the brand. Never mind the gewgaws, or even price. The three most important aspects of a pack are fit, fit, and fit. The pack must fit your body. It must fit the gear you're putting into it (which is why it's recommended to buy your pack last). Above all, it must be comfortable for you to carry with your gear inside (a completely different proposition than weights and sandbags). Pack fit is as individual as shoe fit! If it doesn't fit, you will be miserable.

There are excellent tips on selecting and fitting a pack on the home page of this site.

Treating your pack with care--not dropping it hard, dragging it on the ground, and, when possible, keeping it out of thick brush, will help it last a lot longer.