I’m a trekkie, not a star was fan…but I don’t recall any Borg cube ever being able to destroy a planet in one shot. Assuming the Death Star is fully operational, I’ll give this one to Vader.
Hopefully the fight will be prevented by Velma and Willow falling in love. Buffy and Daphne would probably fall in love as well, as each is already in love with herself and meeting an identical twin (except for hair color) would be their ultimate dream.