The Star Rating system (old system)
The Like:Dislike rating system (current system)
Clearly this system. Not only could you decide if you liked or dislike a video, but you could actually vote on its quality. And the video creator gained a much better understanding of what the viewers really think of the video rather than a simple like:dislike ratio which is massively simplistic. And just think, a critic of a film or TV show does not give the film/show a like or dislike, no he typically gives it a star rating or score out of 5 or 10.
To be fair, the feedback is the purpose for the rating system and this gives more feedback, so i like this one