Windows 10 is highly recommended by me,if it is ture that Windows 7 will retire next year,so there is no point in installing it.
With few simple steps that you can install Windows 10:
https://www.androidphonesoft.com/resources/install-windows-10-from-usb-on-new-pc.html
https://www.howtogeek.com/197559/how-to-install-windows-10-on-your-pc/