Compared to the LDA, PW91 offers better accuracy in predicting molecular geometries, reaction energies, and activation barriers. It is also often compared to other GGA functionals such as PBE (Perdew-Burke-Ernzerhof). While PBE is a more popular choice due to its balance between accuracy and computational efficiency, PW91 is known for its robustness in certain applications, particularly in catalysis research.
