On Disney property that (Bay Lake/Seven Seas Lagoon) is the best place in my opinion as it has the most options. The Yacht & Beach, Boardwalk lake is not as fun because it has a lot of wake zones, you can go all the way up to MGM, but you have to go slowly. Carribean Beach, Old Key West and Coronado have them, but they are on a little lake in the resort, not much action.
With the Seven Seas Lagoon/bay Lake you have access to both with very limited wake zones so you can faster, you can get into some pretty interesting areas on the lake/lagoon as well that you wouldn't be able to see otherwise. It is a lot of fun and in my opinion, the best place to rent them from on WDW property.