Both are nice and you can't go wrong. There are a couple of hotels between them on the hotel strip, but the same beach and location overall.

I personally like the JW because of the pools and greater selection of dining options through the connected walkway to the Marriott, but the Ritz is very nice.

If you can get club access to the Ritz, hands down stay there. JW has Club 91, but paid access only as well. Otherwise it's more personal preference based on the type of vacation you want. Ritz is a little smaller and will be more personalized service with JW having a little more activity.