A hearty +1 to using WinForms (as long as your desktop app targets Windows only, of course). The fact that WinForms has outlasted so many other UI toolkits is a testament to its simplicity and ease of use. I still use it in numerous personal projects, and I don't foresee Microsoft dropping support for it anytime in the near future.
I'm still using a few JScript.NET Windows forms applications I wrote over 10 years ago. Works great. jsc.exe is still on every Windows machine, and makes it easy to write Javascript and compile to .exe or even .dlls.