Many people like handlebar bags for easy access to snacks & a camera, and for a handy place to stash a map so that it is easily visible while riding. I don't like the way a handlebar bag changes the feel of my bicycle, so I don't use one. (But wait you say, what about the front panniers? They do the same thing, don't they? True, and that's why I prefer to ride with a trailer!)
I prefer to use just a map case. I bought a map case from Adventure Cycling. It attaches to the handle bars with velcro, and it works quite well for Adventure Cycling maps or for cue sheets. I usually stash my camera in a very small fanny pack, so that solves that problem. And what about snacks? I usually stash those in my jersey pocket or in a pocket of my Camelbak.
"To truly find yourself you should play hide and seek alone."