I use Win10 since the first release. Originally upgraded from Win8.1 on my laptop, it was an awful crap. My A8-6410 APU has never been used so bad. Win7 ran extremely well, Win8.1 worked nice, but I hate that f*****g Modern UI. Win10 was very very very slow in everything. The browser was bad, the media player suite was bad, software that ran well on 7 or 8.1 was bad on 10. A week later, I was setting up drivers on Win7.
Now, I have my brand new computer, based on FX-8320e, R7 360, Kingston 120GB SSD, 8GB RAM 1866MHz. I read about the Anniversary Update, I wanted to try. Downloaded, set up: it currently works way better than the original build, so I tried it on the laptop. It is still quite a crap, but it really works fine. Just had a BSoD, while recovering from standby, bad usbhub.sys was the cause.
If you want a reliable OS, stick to Win7. If you like Metro/Modern UI, Win8.1 is nearly identical to 7, the only difference is the interface. If you want an updated OS, Win10 is the best choice. In work environment, 10 is the worst OS. I personally find it too multimedia-friendly, at home is quite a good system.