The best interface, clearest navigation, and most up to date maps seems to be google maps I run it on my iPhone or iPad. If I have cellular service it is my first choice. Without Cellular service, I fall back on the old Garmin Dezl.
For finding fuel stops, rest areas, walmarts, etc. the Trucker's Path App is hard to beat. It also lets you know a little about the truck stops, so you can avoid the rough ones. Again, you must have cell service.
Ive read many good reviews on the Rand McNally system, but haven't had a chance to take a look.