WinForms is still the easiest way to write desktop software quickly and easily. If you don't need a fancy UI for customer facing work, its a great platform for internal use.
... for some definition of "easiest." Maybe I would agree if you don't need to support a custom look-and-feel (Win32-looking apps don't really fly anymore), responsive layout, high DPI, touch/pen input, system theme colors, accessibility, localization, and haven't learned XAML.
Win32 is the style that Windows apps are supposed to be and what people expect in a Windows app. What are you talking about? In what way does the win32 look "not fly"?
I've tried to use WPF and it was just a major pain and felt like a mess. There is no impediment to "responsiveness".
Where did you get the idea winforms apps don't follow the system colors?
> Win32 is the style that Windows apps are supposed to be and what people expect in a Windows app.
Maybe in the Windows XP era. None of the built-in apps in Windows 10 look like Win32 apps, apart from legacy stuff that hasn't been ported yet and now looks sorely out of place.
Have a look at lazarus (http://www.lazarus-ide.org/). It uses a different language (FreePascal instead of C#), but for me it's much more productive, and the programs written run without any framework and feel much snappier.
WPF and UWP apps are both far easier.