Help me find the perfect bug out backpack!

Currently my BOB is the Bailout Bag made by LA Police Gear. While it's sturdy, with many pockets and compartments for organization, I gradually realized (1) it's really heavy for what it can hold; (2) it doesn't hold much; (3) it's a shoulder bag, which is not as ergonomic. After my CERT course, I started liking backpacks a lot better (we were issued the CERT backpack for the duration of the course). The shoulder bag would be a pain if I have to walk on foot for any distance.

So I'm looking for something
-- Is ergonomic, or at least comfortable to carry. I don't want to put more than 40 pounds of stuff in the bag.
-- Isn't too heavy.
-- Has many pockets/compartments for organization.
-- Has pockets in front of the body, so if I want to get something I don't have to set the bag down.
-- Does not make me stand out. (This, and the weight requirement, may rule out a lot of tactical bags.)

There are probably other criteria that I am not yet aware. Maybe the discussion will help clarify what I need.

Alright, ye backpacking gods, hit me with your best shot! Thanks!