You could perhaps search the different fora here, this question 'Which is the best' has been asked many times before.
But it depends very much on what you would like to do with it. If you want to backup mostly games, you might want to reconsider buying a plextor (which is the best on almost any point), because of its incompatibility witH SafeDisc 2 protections.
If it is for Audio only (or mostly) I recommend Plextor if you want the best quality. Teac is great as well, especially considering their lower prices.
Usually Plextor wins all the awards when it comes to quality, Teac is usually the one with a better quality/price ratio