I somehow like to play difficult champs xD
So if you're up for the challange, Anivia, Fizz, Nami, Jarvan IV, Blitzcrank.
Otherwise, easier champs i play are Garen, Annie, Soraka[/quote]
those arent very difficult champs lol
difficult champions are more or less Vayne (in terms of kiting, she can 1v1 anyone, just so as long as you dont get caught, so extreme kiting is needed against tanks), Vel Koz(more or less how you aim the q), Zed , etc.
the champions you think are best depends on your lane/ playstyle
I would recommend buying the < 3150IP champs at the beginning or just trying the free week champs until you figured out your playstyle. Then you can pick what champs to buy more easily.
My first favorite champ is morgana. It is almost impossible to lose lane with morg against any champ if you play her decently, because of her insane sustain, OP shield, and ability to afk farm. Also she's quite OP <gold because people don't even try to dodge skillshots+have horrible positioning+are too aggressive in lane. If you like skillshot champs you can also try lux, easy to get legendary just by hitting skillshots against weaker players.