Win7 refined the Vista UI and added stability, booted significantly faster, search indexing was improved, and revised UAC (which I had previously disabled) made the feature more acceptable.
Meanwhile I get nothing in Windows 10 other than an interface I don't care for.
Really? Because going from Windows 7 to Windows 10 you get a new Client Hyper-V, Virtual Desktops, Reworked file-copy routines, reduced memory consumption, integration with tablets and pen devices (I've used pens since Windows XP and it's a godsend), reworked Bluetooth stack, Address Space Randomisation for improved security, a dynamic kernel timer for lower power consumption, as well as the things you like such as booting significantly faster, improved search indexing, and even things you're taken along for the ride like DirectX 12, better system level anti-virus, far better treatment of multimonitors....
Basically if all you're grumbling about is the UI then you have no reason NOT to upgrade to Windows 10, best of all you don't even need Classic Shell installed.