There are several rating systems. Which one is the best?

The purpose of a wine rating is to quantify a wine's quality separate from those factors that influence price. Rating systems vary. Some rating systems are based on a 50 to 100-point scale, others on a 5-point scale, etc. Keep in mind when looking at ratings, that the evaluation of wine is subjective. Factors like bottle variability, tasting conditions, and the judges' likes and dislikes will influence a rating. You are the best judge of wine when it comes to what you enjoy drinking. Ratings can be used as a helpful guideline for choosing a wine once you are familiar with the rater's preferred style (if an individual) or the preferred style of those judges whose opinions contribute to a rating.