Help me pick a Navionics card

[ccm]

I am looking for a map card for a new gps and have been looking at the Navionics website for a long time and it seems the longer I look at it the more confused I get. So, I thought I would come to the Salty Cajun experts for some advice. My fishing is split between the marshes in south Louisiana and freshwater lakes in the northern portion of the state. Don't do any offshore fishing. If anyone here fishes these areas and has used a Navionics card I would appreciate your input on what you have and how well you like it.

Thanks in advance for your advice.

Charlie