Harry Potter by 100000000%. I wrote a response to a question asking the same thing about 6 months ago, so I'm just going to copy it into here.
HARRY POTTER!!!! Twilight is full of sparkling vampires, 50 reasons to have a boyfriend, hot guys, and has so much more depth to the characters. Not only that, but in Harry Potter, the bad guys are bad guys for a reason, and nothing's not always as it seemed to be. Harry Potter seems real, it seems to come to life, and there have been times that, although I don't believe in magic, I question if Harry Potter has been made up. Twilight was just one of those books that was popular for a year or two and then everyone forgot about it. It's been almost twenty years since the first book came out and it's gaining populatity with the Harry Potter and the Cursed Child play, Fantastic Beasts and Where to Find Them movie, JK Rowling, Bonnie Wright and Evanna Lynch's work with Lumos and Emma Watson's work with the He for She foundation. Stephanie Meyer only took part in a fundraiser, nothing compared to Lumos, which needs dedication to run properly.
I'm going to stop here because I could go on forever why Harry Potter is better than Twilight, and I would, but I have stuff to do.