I have a four year old Logitech MouseMan Wheel - it gets daily constant usage (at work, where I'm a developer), it is still smooth and accurate.
It has a slightly odd shape that is definitely not for lefties. It has a high left hand edge arch and a low right hand edge, but my favourite feature is the thumb button low on the left side, that I have set up as a double click!
Ta-ra,
The Gremlin.