I dont know much about the model names or such but I have used a TomTom and a Navman.

User friendly wise, it was TomTom all the way.
Switch the unit to On and you're off
All the point of interest stuff, browsing through the menu, and so on was very clear and very easy to use!

Where as the Navman did get confusing at times.
Setting your destination isn't as easy and more importantly as quick the Tomtom.

The Navman was a smaller and slimmer (and much prettier) unit compared to the Tomtom.
But this isn't enough to persuade me into buying one over the Tomtom!