Best champ to main

What do you play? Jungle,. mid, top, bot?
If you really wanna learn this game, go watch others play, you can learn tricks, correct positioning, what to do in certain situations and a lot more. This is crucial in climbing.

Top - Really good right now are: Darius, Irelia, Fiora, Jax, Renektor, Riven.
Mid - Zed, Fizz, Katarina, VelKoz
Bot - Janna, Lulu / Lucian, KaiSa, Vayne, Draven
Jg - Vi, XinZao, Lee Sin, KhaZix, Shyvana.

I can't tell you what to main outright cause I don't know your playstyle nor the dedication to this game. Do you wanna sit and learn a champ that is hard to master and have a great pay off late or just sit down and play meta and win.