You have many, many more options in what sorts of basemaps you upload. I have only every used Delorme products for printing out a specific topomap of an area.
I like Ozi for being able to use aerial/sat photos as well as topographic data. It also has pretty good real-time options as well.
I have Delorme (& NG & Mapsource/Garmin). I don't like it because you have to drill way down to see details then you loose perspective where you are on the map. I do like the Delorme 3D mode for route selection aid. Generally I prefer NG...just got their latest version with 3D but haven't installed it yet... Haven't used Ozi.