What backpack do you use? Both of my Timbuk2 bags have incredible water resistance. I've been out with them in dozens of thunderstorms - the kind where you get

What backpack do you use? Both of my Timbuk2 bags have incredible water resistance. I've been out with them in dozens of thunderstorms - the kind where you get home and have to change out of all your clothes - and I haven't had so much as a notebook page get wet.