[Corvina]

I'm not that familiar with Namie but she leraned her dancing from scratch, she entered Okinawa Actors School with 12 years and debuted with Super Monkeys (an idol band) with 14 years, right?
Kuu just started getting dance lessons with her debut in 2000 as far as I know.
Of course Namie is technically far ahead and is able to hit harder choreographies. She's the better dancer.

I like to see performances from both, though I personally prefer Kuu's passion.