I'd say Microsoft Studio was an innovative desktop platform, and so is the HP Envy Curve. There's interesting stuff happening in gaming desktops, too, including VR add-ons.

If you include laptops as part of the "traditional desktop ecosystem" then there are lots of innovative 2-in-1s, detachables and convertibles, including the Lenovo Book (a laptop with no physical keyboard).

The "traditional desktop ecosystem" in the form of Windows has also added a lot of features from the mobile ecosystem including sandboxed apps maintained from an app store, notifications, and a voice-controlled AI (Cortana).

The mobile world has reached the stage where you have to look pretty closely to tell one high-end phone from any other high-end phone, and the tablet market is in steep decline. The PC market looks quite innovative in comparison.