I own Ahri, Ali, Annie, Ashe, Azir, Braum, Corki, Ekko, Eve, Ez, Fiora, GP, Garen, Gnar, Heimer, Jayce, Kass, Kayle, Lucian, Lux, Yi, Nid, Poppy, Riven, Shaco, Sivir, Soraka, Syndra, Tahm, Teemo, Trist, TF, Twitch, Udyr, Vi, Voli and Yas.
Of those, I play Ahri, Ali, Annie, Ashe, Azir, Braum, Ekko, Eve, GP, Gnar, Kass, Lux, Nid, Shaco, Sivir, Raka, Syndra, Tahm, Vi and Yas. I have both good and bad games with all of them, but more often than not, I have horrible games. Doesn't matter how perfectly I play my champ, doesn't matter how well I know who I'm up against, doesn't matter if I know exactly what I need to do to beat people, it just never ends up that way. I can land every ability, every skillshot, everything... but then I get clicked on and instantly explode with no chance to dodge or anything. Can't dodge targeted abilities that deal half your health in one hit.
However, some champions are just far too easy and do far too much damage. LB? Yeah, my first game I went 19/1, and only ever died because I dove their entire team. Fizz? 18/6. Yi? 18/5. I felt like I was cheating playing those champs, because I had no idea what I was doing or anything, but still just absolutely dominated my lane.