There are options for good boat paints, but it kinda depends weather you have the equipment to spray or not. All of the "best paints" are toxic, and some are spray only...so equipment and personal protection could be required.
Heres a short summary if thats all ur looking for.
True Linear Polyurethanes are considered the best by industry pros. They include brands like Awlgrip, Sterling, System Three, Interlux, Alexseal, and some others. (Spray or brush/roll)
Just behind the LPU's:
Acrylic Urethane and Hybrids like auto paint and truck fleet paint, imrons. Dupont, PPG, BASF, Sherman Williams, Awlcraft, Martin Senour, and others. (Spray only)
All are 2 part paints and can get very pricey depending on color.