Most people say the lake in front of BWV is small and less interesting. Contemporary and WL are on the same lake, so it probably doesn't matter, but it's a bigger, more interesting lake. The small boats, or "Sea Raycers", are $24 per half hour.
All the boats in the non-monorail resorts are set to go extremely slow, so much so that they're often hard to control if caught in the wake of a larger boat. The ones around MK are the speeded up versions. The slower ones can be driven by anyone 12 and up, the MK area ones require a licensed driver.