I'd been using a backpack for a while and wanted to try out a messenger bag. After trying a few, I settled on the Peak Design Everyday Messenger. For me, the 13L size is the right balance of storage space and profile. I don't use cameras, which seem to have been in designer's mind, but found the flex/fold dividers to be very useful for various gear.
The only improvements I would suggest: The top flap really won't stay open unless you hold it, requiring two hands to dig around inside. It's reinforced in that direction too, so folding it over the other way would probably ruin it. The side pockets are the real reason I chose to try this bag, but they are stiff and kind of hard to use, with very little space.
The V2 bag is nice but it's smaller than the V1 bag and won't hold everything that I carry on a daily basis. I'll admit I've got my V1 stuffed full but it was disappointing that they didn't offer that size with the V2.
I recently purchased the latest version of your Everyday Messenger bag. I love the bag except for one major problem. Why is the material that the bag is made of so stiff? This makes opening the bag difficult & keeping it open almost impossible. Fix that issue & it becomes a 5 star product.