I use Insight Genesis, the Navico product. It is very user friendly and quick to process from upload to your merge and finished map. If you don't feel like, or have the time to log your own surveys, you can visit the Social Maps area on the Insight Genesis site and go through that list of bodies of water, which, is ever growing. You can use the 'bottom hardness' and 'vegetation' layers to help find the fishy spots. One of the most important features to me, is the ability to review my uploaded tracks (recordings), and when I find hazzards, holes or humps and even trees, I can add waypoints, save them and download them to an SD card then load those waypoints to my head units.
Here is a combined screen shot of Shaver Lake in Fresno County. The top portion is with an 'off the shelf' mapping card and the lower part was done with Insight Genesis.
I chose to create my map with 5' contours but you have the option of changing that.
In full disclosure to the forum, I am actively on Pro-Staff with Lowrance, Scotty Fishing and Shasta Tackle, however, I will try to be unbiased where I can.
Edd