I'd look at Kaka myself. His achievements with his club and country must make him favourite. And if we're honest, he was breathtaking against us in the ECL, even if our defensive injuries made it easier. With the talent we've got, he's still one of those players you have to say, 'Damn, I wish he played for us.'
I do agree Ronaldo should be up there too. Achieving what he did in the context of what had happened at the World Cup is impressive, and he's been a key player for his country too.