Ultimately, the Highlander won out because of versatility, extra space and price, but my point in telling you all of this is that when Lexus unleashes the RX L, it will be a very, very hard time for Acura and Infiniti dealers. The interior of the RX feels 2 classes above the MDX and at least one above the QX60. The RX also outshines both on the road with passenger comfort, smoothness and powertrain refinement. The MDX drives kind of hard and while it handles decently, it doesn't give you the same feeling of quality and solidarity that an RX does. QX60 felt slow and unresponsive because of the CVT.
I mean this is pretty much a given. Honda/Nissan has basically given up their premium effort so it shouldn't really be a surprise Lexus' bread-and-butter models crush competitor's abandonded child comfortably. The RX-L will be extremely hard to beat and I doubt anyone will even bother trying to compete against it.