I've carried a FAST Pack Litespeed from TAD Gear[1] almost everyday for the past 3 years. Before that I was mostly using various larger backpacks and a Timbuk2 messenger. The Litespeed has held up really nicely. I use it for both work and whenever I go hiking or camping. It nicely fits my MacBook Pro 13" and my daily things. My main concerns with purchasing it were the price, I believe I paid $245 plus an additional…
However, if you don't care then there's nothing wrong with it. My normal backpack finally wore out, so I've been carrying my Mystery Ranch Assault Pack to work.
I'll probably find something a little more civilian looking, but until then it's a great backpack.