Well, here it is. I haven't actually played the game since early Season 7 (Can't believe it's been almost 2 years), so my opinions may be a little outdated. Nonetheless, this is also partially based on other tier lists, so there is something to this aside from what I think. Nonetheless, it is mostly what I think from watching a few league games, combined with my opinions and my knowledge of changes since I actually played the game, so it could be a little off.

Top Tier: Sion, Darius, Viktor

Strong: Irelia, Urgot, Garen, Teemo, Jax, Yasuo, Riven, Akali, Aatrox, Camille, Kled, Fiora, Renekton

Decent: Yorick, Pantheon, Illaoi, Cho'Gath, Nasus, Shen, Rumble, Gangplank, Singed, Poppy, Swain, Jayce, Kayle, Wukong, Quinn, Vladimir

Usable: Kennen, Jarvan IV, Pyke, Lissandra, Dr. Mundo, Tryndamere, Nautilus, Heimerdinger, Rengar, Maokai, Ekko, Cassiopeia, Karma, Trundle, Vayne

Weak: Gnar, Ornn, Talon, Xin Zhao, Graves, Galio, Olaf, Mordekaiser, Ryze, Tahm Kench, Fizz, Lulu, Leona, Vi, Lee Sin

Bottom Tier: Zed, Blitzcrank, Thresh, Udyr