I notice it's for a friend.. you should go shop him and see what he likes..
there are lots of things to consider, and alot of things only he can tell you.
what are all the equipment he has or will have?
does he prefer a bag to just hold 1 camera and 1 lens, or 1 that allows for future expansion?
type of bag? (backpacks are more comfortable, but not as convenient as shoulder bags)
amount of comfort? (some prefer certain bags over others after trying)
design? (you could probably figure this one out..)