IMO, Logitech make the best mice.
Razer make really good mice, their top end mouse is a bit better in terms of specs.
However I prefer having the shape of Logitech mice a lot better. really easy on the hands.
I have an MX-510 and a G5, and I love them. After using them for a while, I don't like using a "normal" mouse. they just don't track well compared to my Logitech mice.