Windows 10 for work and games, GNU/Linux for privacy. Windows is just decades ahead in term of optimization and compatibility but i wouldn't trust it with sensitive data.
Do you want to be a trader or IT geek? Traders go for the thing that gets them up and running fastest. IT geek love to mess with tech but make no $$$ at the end of the day. Win 10 is much closer to win 7 than Ubuntu.
I changed my OS on my laptop a few months ago... from Win10 to Linux. My reason was that my laptop was just getting slower and slower... the change definitely helped. But... It's not an easy OS to use. I don't really like it, since it's more technical... takes me too much time to add new programs etc. So... If I would buy a new laptop or pc, it will be Win 10 again....
for programming purposes I think linux (without a window manager) is a lot easier. If you're planning on using it as a desktop then ms windows hands down
IF the software you want to run will run on GNU/Linux, it will run faster than on Win 10. (music, monitor color calibration, etc., are all mind blowingly better with GNU/Linux, typically upon install; but this is not your concern for trading) GNU/Linux will have a learning curve. If you're not technically inclined, you may wish to avoid that. However, the total effort is significantly less than I've spent fighting Windows over the years. As in, effort per box is significantly less with GNU/Linux than with Windows. That said, if you go with a trading-dedicated machine (below), it will be more time/effort to get your first GNU/Linux box up and working as you want. A common recommendation is to have a machine that is dedicated to trading, NOTHING else. That greatly simplifies both the maintenance and the risk.
Windows 10 has a decent user experience but you have to deal with a lot of garbage when coming from 7. First it's all the spyware that is pre-installed and sends all sorts of information out, Spybot and the likes help to disable most of it. Then it's the utterly dumb way it updates itself, taking a lot of control away from the user - Windows 7 was much better in this sense. Driver compatibility and the ability to play games makes Windows more user friendly, it's why I prefer over any Linux OS.
I play modern games on Linux all the time, using Steam, but there are also other ways. Firefox/Chrome supports DRM (ugh) for Netflix etc. You may need to install graphics drivers manually though, to get the proper drivers for your GPU. Otherwise, most works but need some more initial tweaking than on Windows, but then much less, more stable, secure and private.