Ajith is the best because he acts in new movies that wasn't already released in other languages. But, vijay all ways acts in movies which had already became super hit in other languages like telungu or malayalm. Ajith acts in many different rolls like 'varalaru' but vijay always act in masala movies, same kind of character in all movies like 'mathura, thirupachi'! They both good but ajith is better than vijay in my way of thinking.