I own a razer (diamondback).
Basically,
Logitech: Fit hand, larger size
Razer: Like an old £3 logitech shape, but sleeker, doesnt fit my hand at all, infact 2 fingers and thumb hang off the side of it. Probably quicker as less weight on mouse. Oh and for me atleast the sidebuttons are awkwardly placed.
So its your choice really, whether you like the mouse holding your hand or not really. Next time might go logitech, but really a mouse depends on your hand size.