Hi Cosine,
Well i have back pack called tamrac expedition three. I dont seem to use it much anymore.
But i just invested in a waterproof port. It holds my two cameras and five lenses and its waterproof. I also have a pouch that i do up around my waist for weddings and trekking. It holds spare battery, cards and two lenses.
So really depends what you are going to do.
Takecare
Chris