Also, proper High DPI support in both WinForms and WPF in .NET 5+. There is starting to be a very notable difference there between applications compiled on .NET Framework (or VB6) versus those recompiled for .NET 5+ WinForms/WPF with older apps not just looking dated, but sometimes aggravatingly unusable/inaccessible on modern monitors.
I don't think I've ever seen a WPF app broken on hi-DPI, and I use a 4K display with 225% scaling. It was designed from grounds up as resolution-independent.
WPF does in general have many fewer issues than WinForms and the ones I've seen that were basically just broken were all WinForms. There's still some changes to WPF that are noticeable if you are looking for them (mostly in the default controls).
