I really can't believe Thanos is beating Ultron in the poll...
Also, if we're being even remotely faithful to source material, Kang is so much more deserving of being the antagonist in an Avengers movie than Thanos. The villian has so much more history with the team and, arguably, some of the most important story arcs in all of the Avengers' print history (Avengers Forever
and the Kang Dynasty
Also (again), the Hank Pym hate makes me sad.