Ronaldo. No question.
I've said it before, but I'll say it again... I think Bale is making a mistake from a career perspective moving to one of the two clubs in the world that unquestionably have a bigger star. If Ronaldo stays at Madrid, I don't think Bale will ever fulfil his true potential.
Weirdly enough, if Bale stayed here and let AVB build a team around him... a team that includes our potentially incredible new signings (Soldado, Paulinho, dare I say it - Willian - and who knows how good Chadli might turn out to be!)... I think there's every chance he'd be winning medals and getting nominated for the Ballon d'Or right here at Tottenham. But at Madrid he'll struggle to escape Ronaldo's shadow.
And one other thing that hasn't been mentioned... Bale has become a symbol of Perez's ambition at Real Madrid. But precisely because of how political that club is, there will be people there who oppose Perez and who will be rooting for Bale to fail just for that reason. Along with the egos in the dressing room (who won't necessarily be happy at all the attention this young upstart from North London is getting) Bale might find himself in a fairly hostile environment.
For his sake, I hope he rises to the adversity and succeeds. But he's turning down a Sure Thing here at Spurs. A chance to be a legend... the heart of the team that returned us to glory - forever remembered. He's abandoning a legacy.