IMHO, I think Hogwarts. Not only because they're British, but because they have centaurs as well, werewolves, unicorns, trolls, and giants that could beat up the halfbloods. Also, the Greek gods aren't included.
But halfblood, on the other hand, have powers. Percy has Tyson, a cyclops, Percy has water powers, Percy has Grover with the music, they have Athena's cabin, who are wise, and Ares's cabin, who are bloodthirsty...
Who would win?
Here's some information.
1. Percy Jackson is a half blood, half human, half God. (dad is Poseidon.)
2. He controls water.
3. Towards the end, he's nearly invincible, but "Avada Kedrava!" Could easily kill him.
That's all you need to know to compare.
1-2-8, boom, bop, beep, ONE HUNDRED AND FIFTY POINTS FOR GRYFFINDOR.
Someone once told me not to bite off more than I can chew. I told them I'd rather choke on greatness than nibble on mediocrity.
"The loneliest moment in someone's life is when they are watching their whole world fall apart, and all the can do is stare blankly."