From your description of who will use it and how it will be used, don't worry about which one is best. The Garmin Nuvis, Magellans, and Tom Toms will all get you from point A to point B. Since you haven't used any of them and become accustomed to navigating a particular menu (they're all different), one is just as good as another. Go to Amazon and get whichever one you can get the best deal on. It's sounding like you don't care about Bluetooth integration, voice recognition, MP3s, or any other add ons, so you can get something pretty cheap.
Any of these manufacturer's vehicle GPS units will get you to your destination 98% of the time as long as you input the address correctly. All of them will generally get you there efficiently 50% of the time. Meaning they'll always find their way to a location, but not always by the most efficient route. If you use one in your hometown, you'll often think, "Why is it wanting me to go down Main St when Maple is way faster with less traffic lights?" But if you're in an unfamiliar area, getting to your destination is likely more important than getting there by the absolutely best route, and all of them will do that for you.