I use the Lowrance programs quite often and I like them a lot. Most of the people I know us them to. Just plug it into the graph and go, your done. Never used the navionics programs. But IMHO I'd go with Lowrance just for the fact that they are used more and if you are fishing in a buddies boat that has a Lorance GPS you can bring your chip and fishing will be a lot easier to do since you have all your hot spots.
"If people concentrated on the really important things in life, there'd be a shortage of fishing poles."
Dave