I have a Sony a7rII, and I use all of these bags with it. The Lowepro toploader zoom 50 AW II gets used if I want to bring my camera and something as large as my Sony 24-70mm f/2.8 G master lens. This bad is also great because the strap detaches and you can clip it onto the shoulder straps of a larger backpack. This is how I travelled in Canada. Possible negatives? There’s not much. It’s pretty epic. I’d say it could be better sealed against moisture perhaps, but I put my camera inside a cuben fibre bag when it was really rainy.
The Lowepro toploader zoom 45AW II is considerably smaller than the Lowepro toploader zoom 50 AW II. I use this when I want to take my Sony a7rII and something like a Zeiss Loxia 50mm. Negatives? The same as above–it could be sealed better. It’s the same style of bag.
The Lowepro Photo Hatchback 22L Backpack is great for a dayhike. You can fit a bit of food in there, lots of lenses and whatnot.
The Crumpler Muli 7500 is also good for day hikes. It’s a shoulder strap type bag, but you can get at the lenses and camera easier. The negatives are that it’s not as good if you’re climbing mountains and whatnot. For street photography, I’d say it’s great. It doesn’t scream camera bag either.