Updates are important, get free ones if they offer them. I've had both TT and Garmin, both worked equally as well for me. If you're driving a truck/trailer or RV, some have the option to re-route you based on the type you're driving to make the trip easier (less scenic, but easier). The wider ones usually have a better screen for typing on when you need to.
I actually use my android phone now as my gps, don't have to carry both, it was free since I already had the phone, and free updates...even has voice navigation.
just my .02
To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault