Let me see. The creation of the greatest GIF in the universe? Facing down racist taunts and jersey-burners? The stamping of Van Persie's face? The fact that beating Arsenal was still a big deal then (I think City hadn't ever beaten them in the Prem era until the year before)? The fact that he's in the greatest kit City ever had or will have?
There's only one to vote for.
Edit: City beat them once in 06 and then in 08 before Adebayor. Before that was 91.