When I run I like to have my hands free, so hand held water bottles don’t really work for me. I have tried bum bag/hip bags to hold water, food, keys, phone etc and these are fine, but do bounce around a bit, and are not ‘ideal’ for accessing water etc as you have to reach around – not very easy when running, especially off road/trail running.
I have recently started using a trail vest, and this is now my ‘go to’ pack for running. The vest sits snuggly and does not move or bounce, even when full of kit. I have my water either in a hydration bladder inside for longer runs (e.g. 2l of water) or have water bottles (I use a soft water bottles) in the front pouches on the shoulder straps – very easy to access when moving. I also use these for gels etc on longer runs. The rear pouch I can then stash keys, food, lightweight jacket, etc.
For me, the vest is a great solution to carrying kit and water whilst leaving my hands free to aid running balance off road, over styles etc.