Just finished re-watching Ouran and initially I was worried as it was one of the first anime I ever watched so I was concerned that, since watching many other amazing anime, it would have dulled. This was most definitely not the case. Every episode still made me laugh, I still thought the script was amazing, the characters and their development extremely well done (apart from Mori, who I still think could have used a little bit more background), and the animation and music/sound brilliant as well.
Very glad to still have it in my 5/5.
After I've finished reading the XXXHOLIC manga, I might pick up the Ouran manga as I know the endings are different at least.