All time favourite : Gangplank! Diversity, Global Presence, Oranges
AP Carry : Kassadin! First champion I played in LoL, I love his burst, and his mobility allows for big plays.
AD Carry: Not that much into ADs but Draven is the one I like most. His skin=PWN,I like the axe catching mechanics, and can do some plays with ult or W.
Support: Kayle and Blitzkrank. I'm not into supports, though Kayle as an AD support works wonders sometimes. Just harrass like theres no tomorrow, and if you somehow manage to get fed, your team has 2 AD carries. Plus, invulnerability on Ulti. For blitz, just DEM HOOKS
Top: Darius. Incredible presence, awesome damage, quite tanky if built right.
I main as a jungler and my personal favourite is: Nunu! He can counterjungle those 'mumus pretty hard, impossible to catch, fast clear speed, awesome ganks.
---------- Post added 2012-08-08 at 11:04 AM ----------
Hmmm after a bit of thought though, I would have to add Shaco as a tie to Nunu. High risk, high reward champion, but I really love the mind tricks you can play on the enemy team, especially early and mid game. Too bad that the current meta is not the best for him.
Tristana. Most people leveled to level 30 with her, and she was their first champ. She is easy to play, and once you master her skills she is completely deadly in any duel or teamfight. Has great escapes, an amazing attack speed steroid, and easy to farm with. I have had times where I couldn't do anything, but those have generally resulted from aggressive opponents and/or passive support.
My favorite champion, god i have so many, but if i have to pick i would say Draven, he reminds me on Warluigi and he is is plain awesome and strong carry, Zyra, LB and Mordekaiser follows after him, but its hard to decide which one i like and which not due the fact I simply have to many, and heca + Shyvana are awsm aswell, oouh to many champs, well but I stay with Draven
Welcome to the league of DRAVEN! *g*
AP: Cass or Vlad. Two different playstyles but both equally fun.
AD: Jax. I don't really like ADs but I don't mind him.
Support: Sona. She is just a beast when she gets rolling.
Tank: Alistar. Do you focus him to prevent his CC but take forever to kill him? Do you leave him alone and let him CC the crap out of your team? They always pick the wrong one.