My team is in the process of migrating a large Windows app from a legacy language to C#. After evaluating the various UI options, we've reached a sad conclusion: MS doesn't actually have a viable UI framework for business apps at this time.
Windows Forms - legacy, in maintenance mode. Shouldn't be considered for new app development.
WPF - A single update, a few years back. Cringeworthy level of complexity and tooling suckiness, can't even subclass a button without having to copy-and-paste XAML from the parent. Seems unlikely to be considered "best practice" for much longer.
UWP - Too new, only has basic UI elements
It seems insane, providing business solutions was supposed to be MS's bread and butter.