You've got two camps:
Razer
Logitech/MS
Try both, personally I HATE Razer mice as they feel horrible to hold. Logitech are moulded perfectly, and the MX518 is the nicest mouse to hold IMO. Im using an MX600 at the moment (kb/m set) and its pretty much the same size.
The G series feel too "tall" IMO and I can't get on with them.