MHO is Cabo, if you limit yourself to the Westin. Cabo location is inconvenient unless you rent a car.
Puerto Vallarta if you do not limit yourself to the Westin. I would recommend the Camino Real which no longer has any affiliation with the Hilton. (Reviews are in the H* forum). Puerto Vallarta has more to do in the way of dining, shopping, walks in the jungle.
Cabo has more drinking, better snorkling, whale watching in season, quite a few good restaurants, but no jungle. It is arid and hot.
Both are enjoyable in their own way.