Great thread! My recommendation is to find a bag and train with it, e.g. run around with it, see how it works under physical exertion, a little stress, etc. My personal thing is that I need a med bag that I can strap/sling/clip to me so I can be hands free and have access to all the necessities and not block other gear on my belt or whatever. I recently bought our entire office the NAR Squad bags that can be strapped on fanny pack style and are clipped behind the driver headrest in their vehicles. I have one of those Vertx sling bags work gave me that's now a trauma kit in my personal vehicle, so it can be slung and I can roll it forward to get to stuff. Other people don't need this hands free consideration, which is fine, but it only makes sense to feel it out first.