I cannot comment on INTERLUX or AWLGRIP paints because I quit using them when I found I could buy IMRON cheaper from local commerical suppliers

System 3 is not as good as IMRON. It makes a great Aircraft, Bicycle, boat deck, etc paint. However it's not what you want to paint your daggerboard or hull bottom with

IMRON is available in several formulations including water based like System 3. The availablity and cost of various formulations in your area will depend on the local market. The auto/industrial oil based is almost always available and the cheapest. It's top of the line custom car paint. Very pretty and very durable. The water based will cost a little more and will be between oil based IMRON and System 3 in durability.

One thing to keep in mind. These things don't even look like normal paint. They almost all solids, very little liquid. So, stir, stir, stir,....

Bottom line- When I repaint my boat, I will spray water based IMRON