I kind of wish Microsoft would just continue development of WPF. I've used it for years for various projects, and there is a learning curve but I've since enjoyed working with it. XAML, data bindings, ViewModels... all of it I actually like. But, WPF needs a few improvements to really make it perfect. I tried several of Microsoft's newer frameworks and the open source ones (Avalonia, Uno), but I either couldn't get the sample projects to even build successfully on my machine, or I never got comfortable with development workflow, and went back to what I know.
My big idea to fix WPF is to rebuild the data binding system to use the .NET compile-time code generation feature instead of run-time reflection. I think that would solve a lot of problems. For one, projects could do an actual AOT build of their applications (right now, you either need to rely on an installed .NET runtime or "publish" the project with a lot of .NET libraries included for self-extract, bloating the final file size). Code generation would probably improve performance quite a bit too, maybe open up the possibility to compile for cross-platform, introduce type safety for XAML bindings (rather than getting vague runtime binding errors), remove the need for so much class scaffolding, etc... I've thought about starting an open source project to do it myself, but seems like a pretty big task and I would essentially be starting a project to help with my other project which I already don't have enough time to work on...