Arrow's Ra's, due to the fact that he lived and trained for more than a lifetime plus that he is shown to be a formidable opponent.
Still, it can't be as easy as some of you say here:
1.Batman's verse Ra's al Ghul wasn't trying to kill Bruce in the sword fight, he was trained him.
2. The fight in the train was barely won by Ra's al Ghul till he realized that Batman had other plan than just stopping the train.
3. In the last fight Batman's had he's armored suit and all his toys..unlike arrow.
Still, i'll give it to Arrow's Ra's al Ghul due to the fact that he has a lot more experience than the Batman's Ra's.