I love my Logitech VX-450. The 4-way scroll wheel is nice, but the defining features are the receiver that fits in the bottom of the unit and the laser tracking. The laser works much better than the standard optical mice for tracking on irregular surfaces. I use mine on my pants leg, sofa, etc.

I have a Logitech bluetooth cordless desktop system at home. I have to say, Logitech's proprietary wireless does have less latency when you first start moving than the bluetooth, but after you've begun motion they are about the same - if that makes any sense.