I am running Yokohama's on 16" (on when I bought the car) and the ride is quite firm, so I would not recommend them and I will be changing them soon.
I have recently started working for a major UK tyre distributor and handle all types and makes of tyre everyday, and it is amazing how different the various brands are. I am finding that even though the sizes and specs may match, the strength/firmness of the walls vary considerably along with the weight of the tyre.
Again, looking at the same spec of tyre, I have found Yokos, Bridgestone and Dunlops appear to be heaviest and have quite stiff walls. Obviously the economy brands such as KwikFits Arrowspeed are lighter, will wear quicker and probably won't perform well under the weight of our cars.
Most of the quality car dealerships that we supply seem to order Pirelli or Continentals and I believe the P6000 with a "J" marking was put on both the the X and S Types at the factory, so they may be the best option for comfort. However, this is not a recommendation, just my own thoughts and what I will probably be changing to.
Good luck.