I ve got a nice and big lowepro vertex200 backpack (1 body, 4-6 lenses).
but what I dislike is if I need to change the lens i have to put it down on the ground(on backside)
and open the full backpack to get inside.
-->perfect would be a backpack with upper and lower compartment.
a big upper compartment for frequently-used lenses!!
and a lower compartment for body, other lenses, accessories...