In addition to the choices in the poll, I've played Savage Suzerain (Savage Worlds with twists), Suzerain (Mojo Rules! system), Savage Worlds, RIFTS, Mage, and probably one or two others.
I joined a group with the goal of trying as many game systems as possible. What I played:
a session of Don’t Rest Your Head
a session of Donjon
a session of Dungeon Slayers
a session of My Life With Master
a session of In A Wicked Age
two sessions of Warhammer Fantasy Roleplay 3rd edition
a session of Polaris
two session of Mountain Witch
a session of Robin Laws’ Feng Shui
three sessions of Dogs in the Vinyard
two sessions of Warhammer Fantasy Roleplay 2nd edition
a session of Paranoia 2nd edition
three sessions of Spirit of the Century
a session of Labyrinth Lord
a session of Western City
a session of The Shadow of Yesterday
a session of Burning Wheel’s Blossoms Are Falling
Outside of this group I also played Three sessions of D&D 4E.
And in my regular campaigns I played:
A Song of Ice And Fire
Mongoose Traveller
Diaspora
D&D 3.5 (two campaigns still ongoing)
Pathfinder RPG (one campaign still ongoing)
Labyrinth Lord (Just started a second ongoing campaign)