The Violin is a bit more flexible, has a bit more feel, loops better. The Yasaka is a tiny bit firmer so maybe a tiny bit better in blocks. Although you can block really well with the Violin too with correct technique and once you get the hang of it. Neither blade is overly fast. If price is no issue and you love to loop, the Nittaku. Otherwise the Yasaka is pretty much as good but much cheaper.
And which one has more crisp feel?