Like the 'mood' they like to be in, or maybe the evil they enjoy doing. They video themselves beating class mates or some homeless person they love to hate
One Piece - Because it fits the storyline very well and the emotion aswell.
Bleach - If you like Rock & Current Musics.
IMHO, Bleach has the beastiest Openings and Endings I've ever seen/watched.
"With a thrust it's a Spear; with a sweep it's a Naginata, when you hold it, it's a Longsword; a Cane can become each of those things!"-
Bored? Play BattleDawn
"The Best Strategy MMO Browser Game"
I been watching a anime called Gintama lately and it has some of the best music tracks i've seen in anime (aside from when they sing as a joke)