Best advice any one ever gave me was this - you want a TWO BAG system. Your main BOB is one bag and then attached to it is a HAR Bag - Haul Ass and Run
Example:
Your BOB may have 3 days of food - HAR has 1 day.
Your BOB may have a walkie talkie - HAR has a signal mirror.
Your BOB has a trauma kit - your HAR has a few bandaids.
Got it?
Now take all of the things you want to put in these bags and start saving them some where. You can put it in a tub from Walmart or just use the guest bedroom - but start your stockpile where other family members wont be filching crap out of your bag stash. It drives me crazy when people violate the bag with out so much as a word that I need to replace something.
When you think you have the items you need to put in your BOB/HAR then look to see how much size you need. Only then will you buy the right bag.
If you buy before you have a stash, then you will either get one too small and not have enough, or you will get one that is too big and that space will get filled with more BOB stuff - but usually unnecessary stuff.
All of the manufacturers you have mentioned are great. So is VooDoo Tactical. Right now the DOD is de-issuing a lot of the gear troops have been carrying and they are getting a new backpack style. That means gently used backpacks will be hitting markets soon. I'm holding out for battle tested at a discount.
If you want your HAR bag can fit INSIDE the BOB. Or... If you get a M.O.L.L.E./P.A.L.S. bag, it can strap on the outside for reasonably quick detatchment.
