If you trust Microsoft and the US Government with your private keys then by all means use Windows 10. I use GNU/Linux and I must say that I trust the US Government way more than many on this forum.

As for staying with Windows 7, why keep fighting change? The direction that Microsoft is heading in has been very clear for a very long time. I moved to GNU/Linux back in 2006 since at the time I did not like the "vista" on the horizon.