I was in your same predicament 3 weeks ago. For quite a while, I was looking to invest in a fanny/lumbar pack. I looked at many models: Maxpedition DevilDog & Versipack; Mountainsmith Tour & Day; and Kelty Hawkeye, Cardinal, and Kestrel models.
I finally went with the
Kelty Hawkeye. 800 cubic inches, plenty of space. However.....
I recommend not looking at a specific pack, but assembling your survival/urban/"oh crap the world is ending" kit
FIRST....
THEN buying the pack accordingly to fit your needs. That is what I did and it worked out for my needs best. Don't just buy a pack to buy a pack, plan accordingly, assemble your list of items, then get to it!