I tend to use this for the gym - though it is more versatile than that.
It's the perfect size for a gym bag. When under-filled, the pocketing slims down nicely to drape well when being carried off one shoulder, or cross-body.
The O-rings in each compartment make it easy to attach smaller organizational items as needed. I put Grab Bags inside of it (because overall this bag feels like a 10x bigger version of the Grab Bag!). If you want a stiffer version, get the ballistic. if you want it more lightweight and crushable get Halcyon or Cordura (I've got Cordura).
The end loops are great for hanging the bag vertically in a locker, or in a closet for storage. Grab handles are angled inward to make it easier to carry cross-body without them interfering or bending in a way that's annoying.
For a sense of size, the big main compartment can zip close with a football in it, but not with a full sized basketball or soccer ball. Those can be carried in it securely, but the bag won't fully close.