[davidr]

Currently I am using a Zumo 500 with a 4GB SD and a 276C, although over the past few weeks I have also been using a Nuvi 650T, Nuvi 350T, Quest and 60Cs (I sell Garmins on the side and so regularly try out new ones)

Main Advantages of the ones I have looked at:

Zumo 500 with SD card: Good Value for money with most of what motorcyclists need.
GPSMap 276c: Great for doing track recording and excellent screen size and quality.
Nuvi 650T: Nice wide high quality screen and cool for the car with TMC
Nuvi 350T: Good Value for money and handy with TMC
Quest: An old favourite of mine on the motorbike, also good also for cycling
60cs: A rugged little unit with lots of nice trekking and adventure features although not cheap.

HTH.

David