Since Windows 7 will eventually go the way of Windows XP and be kicked to the curb, I have been looking to eventually upgrade to Windows 10 on our main PC. I'm reluctant, but it's inevitable; while Windows 10 is not horrible (at least, not after a few major upgrade releases) it's still too automated and nosy for my liking.
You can still upgrade from Windows 7 (and indeed Windows 8.x) to Windows 10, although you will now need to purchase a license, as the free upgrades are over. Personally, I wonder if they will come back for a period around the time that support ends for Windows 7 in January 2020, but who knows?
I prefer to go the fresh install route myself, then transfer user data to the new OS. Wouldn't you know, Microsoft has pulled Windows Easy Transfer from Windows 10 now too. While it was not the best software in the world, it worked well enough to semi-automate migration from one PC to another.
You *can* faff around and use the Windows Easy Transfer of the Windows PC, then copy the guts of it to the Windows 10 PC and run it from there, but there are also free 3rd party tools to do that.
Of course, you can always just manually copy the appropriate folders from one PC to another (or from Windows 7 and then reinstall after you have installed Windows 10 on the same PC).