GWX control panel all the way. You might get W10 for "free" now but sooner or later the monthly charges will start. Google for which updates to hide and not download/install-here's some: Especially KB3035583!
KB2952664 Compatibility update for upgrading Windows 7
KB2990214 Update that enables you to upgrade from Windows 7 to a later version of Windows
KB3021917 Update to Windows 7 SP1 for performance improvements
KB3022345 Update for customer experience and diagnostic telemetry
KB3035583 Update installs get windows 10 app in Windows 8.1 and Windows 7 SP1
KB3068708 (replaces KB3022345) Update for customer experience and diagnostic telemetry
KB3075249 Update that adds telemetry points to consent.exe in Windows 8.1 and Windows 7
KB3080149 Update for customer experience and diagnostic telemetry