It's kind of a crapshoot to me. They both have the same GENERAL rules (hit X lit targets to light locks and start multiball). WW has some more "stuff" going on...multiple scoops, ramp that opens, back drop target, spinning discs. I like them both a lot, but prefer ES by a nose, but that's all personal preference at that point.
Price wise you're probably at 2,000 for ES and 2,300 for WW +/- based on condition/location.