Where does Switch have the biggest marketshare?

Tales of Berseria, which was the last release in the franchise opened like ~4k in the UK according to VGC estimates so not much of a victory especially when the differential in sales is not even a fraction of the Japanese versions ...

Japan

I wasn't claiming it was some massive "Victory" i just said it was a major surprise, given that the PS4  has a much larger active userbase, particularly in the U.K.

My guess is games like assassins creed and red dead redemption on the ps4 had a massive impact of tales of vesp for the ps4.

In the grand scheme of things, I don't think it's all that of a big deal considering the franchise does less than 10k units in the UK and consistently accounts for less than 10% of the total sales in Europe ... 

What makes the PS4 attractive among many smaller 3rd party Japanese developers is it's entirety and that they see relatively strong sales in a lot of regions rather than just a several ...

Maybe also the same happened in Japan, but the other way round. Tales of Vesperia did come out together with NSMBUdx

8% share for Xbox...

And people wonder why xbox toned down its japanese game efforts..

You're kind of making the same point as me. Nintendo is historically quite weak in the U.K., therefore for a same-day 3rd party release to outperform its PS4 counterpart is pretty news-worthy imo. You are probably right, there is a small market for the game in the U.K.  but nonetheless, if it performs well for Nintendo in their bigger markets it bodes well for future 3rd party releases. It seems to be doing quite well in Japan from what i can make out and in other markets in Europe, Switch is more competitive, so it should perform better in those markets too. I guess we should see how it goes in the U.S. before we start saying it's a WW success though.

It was competing with NSMBUD same day on Switch, too.