Determining the "best" restaurant is subjective and depends on individual preferences like taste, ambiance, price, and location. However, I can provide a few well-regarded Thai restaurants in Chennai that you might want to consider:

• Benjarong:

  Often considered one of the top choices for authentic Thai cuisine in Chennai. It's known for its elegant ambiance and extensive menu.

• Khao San Road:

  Offers a more casual dining experience with a focus on Thai street food. It's known for its vibrant atmosphere and flavorful dishes.

• Maplai:

  While primarily a South Indian restaurant, Maplai often features Thai dishes on its menu that receive positive reviews.

I recommend checking online reviews and menus, and considering what kind of atmosphere and dishes you are looking for to make the best choice for you.