WPF and Winforms may be stable, but they're not going to work well on a modern machine with a HiDpi monitor. Same with Win32 controls.

My take: Use Win32 for opening windows and interfacing with the OS. Use a different toolkit for actually drawing inside the windows.

Ideally a toolkit that can paint in sync with window open and resize, otherwise you'll get Electron-style window flickering. And something that supports multiple windows in a lightweight way, since you're going to want popups, menus etc. to extend outside parent window bounds