Osprey -- how do I love thee, let me count the ways.  The easy access front of the front flap holds my keys and subway pass (no need to fiddle with straps).  The velcro is SERIOUSLY strong (it was full of stuff, I forgot to close the straps, but the velcro held it shut all the way home).  Cross body style (and strap to hold it snug to the body) means that my hands can be holding on to the kids, NOT my bag, and my stuff is still safe. LOVE IT!