Sling bag? Someone mentioned 5.11... I have a MOAB 6 which i do like but has carry problems, I have to admit. (I've even tried converting it to twin strap carry which is pretty easy). I'd like to try out a MOAB 10 though.
I've both the Moab 6 and 10. Both have strengths and weaknesses.
I found the floating pad on the 6 a bit annoying, so I added a press stud to the strap and pad to keep it in palace, but removable. I like it for walking the dogs as it carries their stuff well and I don't need a major loadout.
The 10 is more comfortable, then strap is great but can cut across my neck sometimes so needs frequent adjustment on the move. Better capacity for larger things but that also brings the problem of more weight on one shoulder. I used it mostly for work but with my lunch box and ipad in the main compartment it was pretty much at capacity. I had to use a side pouch for my Nalgene, which I dislike as it adds off centre weight to an already off centre pack.
The organisation on both is excellent though, the 2 sleeve pockets in the admin section are perfect for maxpedition cocoon pouches (I use one as a booboo kit).
One other thing I found is that the ccw sleeve can affect, and be affected by what is in the neighbouring pouches. I can't carry a gun but thin items like a velcro flashlight / knife pouch fit nice in there - but makes for a bump in the walls of the other sections.
"I used to be an adventurer like you, but then I took a pie to the belly"