Jinx/Sivir are T1, as both have high kiteability in teamfights thanks to their passive/ult and both have elite damage and waveclear.
Graves/Caitlyn are fine for Solo Q because they win lane, but both have their drawbacks if you don't get ahead. They're plenty good enough, though.
I wouldn't play any of Corki/Draven/Kalista/Lucian unless I was very confident, they are all abusable and hard to play. If you wanted a fun champion to pick up, though, I would strongly recommend Kalista. She "teaches" mechanics, too, because people who aren't inclined to move between autos are encouraged to learn how to do it.
I would never ever play Vayne in Ranked, and encourage all Vayne players that think they're the next D-Lift to kindly eat a dick.
Most everyone else is inferior to those guys, and if you want to learn a new champion I wouldn't stray from the first 8. I personally have been enjoying Sivir a lot lately, the ability to buff your entire team and kite around enemy tanks lets even teams that are behind/poor at positioning win teamfights if you play them correctly.