7 also had the most flexible/capable iteration of the Windows theme engine, which enabled the creation of a wide variety of high quality third party themes you

7 also had the most flexible/capable iteration of the Windows theme engine, which enabled the creation of a wide variety of high quality third party themes you could use if Aero wasn't quite your thing but you also didn't want to drop back to Win9x look. 8 gutted the Windows theme engine because most of it wasn't needed to render flat squares and it still has yet to recover.