easiest is jumping off a dock or cliff and doing a misty 5 cause you bounce right into the flip and get to spot the landing really early. just pop hard, throw your shoulder down toward your opposite hip, and look for the landing
fronts are easy too but blind landing makes them a bit tougher, prob should learn that after misty 5
backflip off the dock is easy and safe too. just stand backwards on the edge, pop up and hard, and bring your knees to your chest and get those hips around. you get to spot the landing like almost instantly. only risk is hitting the dock of course, so to be safe make sure you pop up and away from the dock. landing weird in the water is no worry compared to hitting your head on a dock
backy is the best to learn probably because that will likely be the easiest first flip on snow for you. but just like on snow, do whichever one you can truly visualize yourself doing. some people hate front flips, some people are scared of backies, we're all different
the BEST flip on diving boards and cliffs is the front flip and a half though (land in a dive ofc). put that on your long-term agenda, they're fun as hell and people love em