I'm so glad to hear that from someone unprompted. I tried WPF and it was a million times harder to use than WinForms, and I couldn't even be bothered to try out MAUI (although I accept it as an apology for WPF lol). I'm still using a WinForms application every day (Git Extensions) and have been able to contribute to it not least because it's the good old familiar WinForms.

This is not to say that WinForms isn't without its problems. I often wonder what it could be like if all the effort of making WPF and MAUI had gone into maintaining, modernizing and improving it.

Agreed it is the easiest, however it is also possible to use WPF on the same style as Forms, with more features, no need to go crazy with MVVM, stay with plain code behind.

Having said this, from 3rd parties, Avalonia is probably the best option.

While I think Uno is great as well, they lose a bit by betting on WinUI as foundation on Windows, and that has been only disappointment after disappointment since Project Reunion.

We spent the better part of a calendar year researching what framework to update our MFC app to. We really liked the idea of staying first-party since our UI is explicitly Windows-only, and we looked at every framework - MAUI, winforms or WPF with a C# layer, WinUI3...

It quickly became apparent that WinUI3 was the only one even close to viable for our use case, and we tried getting a basic prototype running with out legacy backend code. We kept running into dealbreakers we hoped would be addressed in the alleged future releases, like the lack of tables, or the baffling lack of a GUI UI designer (like every other previous Win framework).

...We're currently writing our GUI in Qt.