I think the main reason people are upgrading is because Microsoft will end support for Windows 7 in 2020. I personally love Windows 7 and will probably not upgrade until security updates are discontinued.
The reason I still prefer Windows 7 over others is because it is very stable and easy to use. When Windows 8 came, I tried it but encountered many problems so I changed it back to 7.
Windows 7 is much better for me, because it is easy to use, to navigate the tools. the system most of the time support most application or software, it consume little bit capacity in hard drive. in terms of games whether offline or online most of the time windows 7 has a compatibility with in some installer. unlike windows 10, in my own view, it was release and design with the latest PC's mostly, touch screen Computer. in terms of the software, I think windows 10 has a limited capability and compatibility.