I have been using iNavx for years, and think it is better than several others I have tried. That may well be because I learned how to use it first . It is at the high end of the price range ($50 or so) but you can use it with NOAA charts that are free, or with Navionics charts that cost about $50 for all USA waters and all Canadian charts for $60. All in all, I don't mind the price of the app or the charts, especially compared to the cost of the equivalent paper charts. I have iNavx on both iPhone and iPad, and like that I can import/export waypoints and routes between the two. Of course, one likes what one is comfortable with; I don't doubt that others have better reasons to like what they like.