Depends on who you ask I guess!
For me it's Bays because it's a gorgeous style, really elegant yet can be worn with a casual outfit as well, and it really suits my lifestyle at the moment. I can fit loads of Miss M's stuff inside as well as my own, and the contents are easy to find so no rummaging required.
That said, I do love the look of Roxy and always will. Just can't get on with the Roxy straps, boxy-ness and the weight of the bag.