In our pool, the kids loved jumping onto those flat rafts, trying to surf (ruined a lot of rafts that way). Or jumping through the center of inflatable rings from the deck. And moving the picnic table to the side of the 6' end and jumping in from it was a big hit.
Goggles and snorkels were used often. We had a pair of swim goggles that were blacked out for playing Marco Polo without cheating.
The boys liked the floating basketball net. I took off the small styrofoam the manufacturer used and put a bigger 'noodle' on so it would stay upright better.
A real raft, the kind you can sit in and paddle was used a lot also. The girls liked to pretend they were going places in it. The boys just wanted to jump in it, but weren't allowed, because I'd buy inexpensive ones and the bottom would come out with jumping.
The throw-sink-fetch toys seemed to only be used there was only one bored kid in the pool.
But the absolute best pool toy, the one most requested by all kids (mine and the neighbors), was me. Having an adult that will actually play with the kids on their level is endless fun for them. They would even play with the throw-sink-fetch toys when I played too. They especially liked to be thrown up into the air or thrown into the water from the side. Or to ride me like I was a dolphin, going in and out of the water. They would wear me out in the pool.
And of course, we would swim a night with the lights out and play with my flashlights underwater. They used the flashlights in the pool more that I did.