I've got a couple of Timbuk2 messenger bags that I like. One is XS size, nice as an everyday manbag. And quite brightly coloured, maybe looks less like a handbag?
I do think its handy to carry my wallet, bottle of water/cup of tea, bit of food, jacket, camera etc. I have a foam insert, which makes it into a nice little camera bag.
A backpack is more comfy if want to carry heavier stuff all day, but less convenient for getting things in and out.
I tried a couple of military surplus shoulder bags, but found the straps not as comfy, and more faff with buckles etc.