i got a deathadder, G9, G5, SidewinderX6, Lachesis and a copperhead.
I can tell you that they are all awsome in their own ways (apart from the sidewinder which is pure fail)

The deathadder is simple and easy to setup/use and tracks very very well for a comparitivley affordable price.. The razer drivers are very customisable but are quite fiddly
the G9 has some awsome tracking, and is very versatile with its exchangable faceplates and weight system.. drivers are easy to use and very customisable
G5 is a lower spec (but very different shape) G9... Its all about the feel
IMO you cant beat the Lachesis... yes the drivers are a faf but the 4000DPI, 9 buttons and on the fly sensitivity change is pure WIN!

but theyre all awsome little devices