I play 2 roles mainly and am only Gold II. Those roles are jungle and middle, though I'm competent in all roles, as you all should be!
Mid: Viktor (#1 atm, he's just too strong), Vel'Koz, LeBlanc, Malzahar, Brand, Azir, Karthus, Xerath (I like mages, not assassins)
Jungle: Zac (#1 always, even when he sucked, I just adore him), Skarner, Nunu, Hecarim, Rammus, Nautilus, Trundle (Always built these champions beefy as fuck, which is even better now that tank jungle seems to be becoming the new meta)