Final answer:
Taylor Swift is the artist who writes or co-writes all her songs, distinguishing herself with her songwriting skills.
Step-by-step explanation:
The artist from the choices provided who writes or co-writes all their songs is Taylor Swift. She is well-known for her songwriting skills and storytelling through her music, showcasing personal life experiences and creative narratives. Kenny Chesney, Garth Brooks, and Shania Twain, although involved in the songwriting process for some of their songs, are not known to have personally written or co-written all of their music to the extent Taylor Swift has. Swift's involvement in the creation of her songs has contributed greatly to her popularity and the connection her fans feel to her music.