Video Game: Probably COD4. One of the best online experiences in my life, and while I enjoyed FF1 and LoZ1 and LoZTP, COD4 had that replay value that really made it #1 for me.
Movie: My tastes change too often for me to nail one down. Maybe Swordfish? Blitz? Face/Off?
Band/Artist: Hard to say. For groups, Fall Out Boy probably gets this accolade. I mainly listen to EDM though, and each new track just sounds so much more awesome than the last, so... no clear winner.
Anime: Tie between Suzumiya Haruhi no Yuuutsu and Chuunibyou demo Koi ga Shitai.
TV: Psych is good, and isn't anime covered by this?
Pokemon: Protip: Not everybody likes Pokemon, but I do. As a GenWunner, Vaporeon is easily one of the best. Super high HP and def with good speed and movelist made him a serious threat. Not to mention looking badass was one of the only ways to play the game.
Book: The Legend of Drizzt. Series by R.A. Salvatore.
Weapon: What kind of question is this? No comment.
Pony: Princess Luna
Drink: Cherry Dr. Pepper
Superhero: Batman don't need no fancy superpowers.
Cartoon: Isn't this covered by TV? Maybe American Dad or Regular Show.
Vehicle: I want a moped.
Celebrity: John Travolta
Food: Shrimp. But try sausages wrapped in pancakes that's wrapped up in bacon, then cover it in syrup. Really good.