This is my personal "tier" list for solo queue ranked.
Support - Orianna, Zilean, Alistar, Blitzcrank, Janna, Taric, Sona, Kayle, Soraka, Lux
AP Carry - Morgana, Annie, Brand, Akali, Karthus, Swain, Gragas, Veigar, Kennen, Vladimir, Cassiopeia, Anivia, Ryze, Malzahar, Kassadin, Katarina, LeBlanc
AP - Mordekaiser, Rumble, Maokai, Twisted Fate, Heimerdinger, Poppy, Karma, Nidalee, Evelynn, Sion
AD Carry - Kog'maw, Vayne, Tristana, Caitlyn, Ashe, Corki, Teemo, Miss Fortune, Ezreal
AD - Garen, Renekton, Irelia, Udyr, Nasus, Jax, Pantheon, Sivir, Yorick, Xin Zhao, Jarvan IV, Twitch
Jungle - Nocturne, Fiddlesticks, Lee Sin, Amumu, Warwick, Gangplank, Tryndamere, Trundle, Master Yi, Olaf, Nunu, Shaco
"Tank" - Singed, Cho'gath, Leona, Malphite, Galio, Shen, Rammus, Dr. Mundo