Stormalong Bay is definitely the best
DVC pool. It has different areas that do different things that are really neat. Of course it has a "beach" where the sand slopes into the pool and the entire bottom of the pool is sand. One drawback though is that it's real gritty not very comfortable on the feet.
Another area is the "whirlpool" where high-powered jets spin the water in a circular area so that you go round and round the designated area. My girls love this one.
My favorite area though is the "sinking sand" where small jets sporadically blow water from underneath the sand so that while you're walking through it, your feet sink into the sand and then they turn off so that the sand "grabs" your feet. Really ingenious.
After all that, it has the best slide hands down. It also has the best little kids slide.
For other resorts, I really like SSR's main pool. There is something very serene and relaxing about it. It also has a great slide. The Grandstand pool at SSR is also a great tranquil pool with one of the best splash pads at Disney.
My least favorite pool is BLT. While the slide is nice and neat to watch at night, the pool itself and the surrounding area has a cold feeling to it as there is really zero theming to it other then the slide. It's also way too small and you feel cramped and claustrophobic if it's crowded.