Because we can't let those elitist chumps over in the DOTA 2 forum trump us!
In general, my frequency of play for role tends to go thusly: Jungler > Mid > Top > AD Carry > Support.
When he's not banned, I love playing Amumu most, though I've been trying to learn Hecarim and often fall back on Skarner or Mundo to jungle. In mid, I play Cassiopeia or Ahri, I go Jayce, Rumble or Irelia top, carry as Ezreal or Tristana, and support with Leona and Janna.
How about you?