The paddle board is good for balance as you stand on it and your core is constantly engaged.
Kayak is a much more fast game and your arms and shoulders will get a very good workout, however your legs will do nothing at all.
I got sucked into buying a K2 a few years ago because my friend is a bit older then me and didn't fancy going on a paddle board; he doesn't like the idea of getting into unknown waters.
I never fell and learned to paddle almost immediately; must be my early days of rowing helping with balance.
In fact, I tell you, those paddle boards are a lot more stable that they look and surely more stable than rowing boats.
