I don't normally post here, but wanted to put in my two cents; I traveled to Langkawi exactly a year ago, and when we couldn't decide between the two, we split our trip between both the Westin and Berjaya.

We stayed in a sea-facing room at the Westin, and although the decor of the entire property was as expected (modern, sleek, clean), some of the property was surprisingly run-down, especially our upgraded room. The infinity pool was great, the buffet was amazing, but the small beach was a big disappointment. It was so rocky and coarse that we spent much more time at the pool than the beach.

We booked a junior chalet on the water at the Berjaya, and both the room and resort surpassed all expectations. The balcony over the water (with amazing view) was really something, and while the room isn't comparable to a five-star luxury hotel, we loved the uncommon bungalow-over-the-water setup. The beach was big and comfortable, and we enjoyed it so much that I don't think we stepped in the pool at all. The public areas were busy (but not crowded), but the area with the rooms are further and very quiet.

Hong Kong and Singapore were part of our trip last year, and coming from big cities, it was great to visit Langkawi. That being said, in a big beach/rainforest/nature place like Langkawi, I'd personally forego the Westin (and maybe even the Four Seasons) in favor of a more "local" resort that you can't find at home, or anywhere else. I'd highly recommend the Berjaya, but I suppose the Andaman or Datai would do as well!