For Windows Desktops
MAUI (.NET MAUI) - The evolution of Xamarin.Forms, officially supported by Microsoft for building native desktop and mobile apps.
Avalonia UI - A powerful, open-source framework known for its true cross-platform rendering and strong support for desktop platforms.
Uno Platform - Uses WinUI 3's API to build pixel-perfect applications that run natively on all platforms, including Windows.
For Linux Desktops
Avalonia UI - Offers first-class, excellent support for Linux. It's a top choice for .NET apps on Linux.
Uno Platform - Provides robust Linux support through its Skia+GTK rendering backend.
MAUI (.NET MAUI) - Linux support is not officially provided by Microsoft but is being developed and maintained by the community.
For Mobile (iOS & Android)
MAUI (.NET MAUI) - A primary focus of MAUI is to build native iOS and Android apps from a single C# codebase.
Uno Platform - Excels at mobile development, allowing you to share code and UI for iOS, Android, and other platforms.
Avalonia UI - Supports mobile platforms (iOS and Android), though it is more widely known for its desktop capabilities.