I have played a good number of The Legend of Zelda series. While they are all great games, none stood out to me like Twilight Princess has.
Everything about The Legend of Zelda: Twilight Princess is amazing. The art style, combat, music, and the story all scream great, and can be considered some of the best of the past console generation. The ability to become a wolf stands out from the rest of the Zelda series, and leads to some great segments.
The story itself also shines in its own right, and helps push the game along at a great pace. The atmosphere for this game is a bit on the darker side, separating it apart from most of the other Zelda titles. I would consider Twilight Princess to be the star of the Zelda series, and an amazing experience for those looking for a great RPG, or a great game in general.