I suppose It's a case of "Horses for Courses"
I've tried Tom Tom, Android and Nokia and even "GPS for Dummies" and the only one I'm happy with is Nuvi.
In fact I can't drive without one anymore. I feel lost without "my trusted companion".
When going for a long trip I even take a spare one packed in a box, Just in case.
Nuvi has also saved me thousands of Rands in Petrol and Toll Fees as I use Trip Planner for Round Trip Deliveries.
I find that other Navigation Systems don't have the finesse of a Genuine Garmin Nuvi.