I don’t know how well each company covers the lakes you are wanting but I would start by visiting each web site and see if you can find out (or perhaps someone here can post a few screen snapshots of the details that their LakeMaster or Navionics mapping cards shows). I do know that the LakeMaster card allows for some unique menu options that the Navionics card does not. More on that here:
Cartography-Gps-Maps