All fine instruments. If you go the Yamaha direction I'd go for the 340 because it will likely be cheaper and they have the same action. And the difference in sounds among Clavinova models is negligible (though there is sometimes a noticeable difference in speaker quality).
Kawai makes some of the best actions in the industry. The CS3 uses the RH action also found in the MP6. It's not as good as their higher end RM3 action, but I suspect it's better than Yamaha's action. I previously had a Yamaha GH action piano and liked it but then I got a Kawai and liked the action better (though it was not an RH action). The CS3 also looks noticeably better than the Yamahs to my eyes. Progressive harmonic imaging is just ok. Personally I prefer the Yamaha sound engine.
If it were me buying and I had those choices, I'd get the CS3 for the looks and the action. I use software pianos to generate my sounds. If you do not intend to do this, then probably the 340 is the best bet for the money from that group.
Of course, if money isn't an issue (or isn't much of an issue), you can walk up in either the Yamaha or Kawai lines. In particular, going up to the CA63 would be a large improvement over any pianos mentioned here. The Clavinovas mostly get better speakers and cabinetry as you go up. I wouldn't tend to pay for that.