Aight devs, let's start a war.

Throw at me your best UI framework yet.

Anything (except game engines), cross platform preferable.

++ for why and how easy/hard to learn.

Kivy
Python, supports plenty of platforms, mobile and desktop
One of the easiest to learn, even for those who don't know oop which is required for most gui frameworks
Very versatile

Will I be thrown into Tartarus for suggesting a web based thing?
Anyway, both QtWebEngine and Chromium Embedded Framework allow you to write apps embedding a browser and use web tech (ye olde html, CSS, JS) to write the UI.

I prefer QT Framework for UI in general. C++, Cross platform, industry supported, big community etc.

xterm

Qt.

Pros:
- Lots of features
- Uses nice and performant C++ with ports to many other languages
- Powerful tools for UI design
- Immense amount of features
- Surprisingly easy to create your own widgets
- Featureful
- Excellent documentation (*cough* Tk)
- Did I mention the sheer number of features it has?

Cons:
- Retarded licensing scheme
- Extreme OOP can make code very verbose and hard to read
- Arguably a little bloated, depending on your needs

Avalonia,
Cross-platform C# desktop apps development

@h4xx3r how widely supported is it?

@Codex404 it's of fresh\ongoing development, based on the latest net core framework. So it's up to you to judge if it does fit your needs.

Ps: you develop in visual studio with graphics

GWT 🍿

Azul for Rust. Or if that's too high level, then GTK

@h4xx3r how is rider support?

Console or service applications. The best UI is no UI, no pesky end users that mess up your beautiful code logic.

@HisAxelency agreed, and better performance!

Tkinter

Pro: It's hard

Con: It's hard

@c3ypt1c I’d say it’s relatively simple. But I do like Tkinter a lot. It should get more credit.

@Codex404 what is rider support? O.o

@h4xx3r

Rider is a Jetbrains .NET IDE. It's fairly new so it doesn't support everything yet.

@HisAxelency Rider supports xaml graphics making?

@h4xx3r

You can create WPF/UWP projects in it, it doesn't have a real form editor like VS does though. You can just edit the XAML manually. At least, that was the case last time I checked (4 months ago).

Rider is focussed on cross platform .Net development.

@h4xx3r as far as I know they do support WPF. Though I have not tried it yet will check to be sure.

@HisAxelency o.O I'm not a XML master, I need a preview of the final outcome.
That's a game stopper for me.

@h4xx3r @HisAxelencyI checked and it does have a visual XAML editor.

The reason why i prefer Rider is its multiplatform. Linux included.

@Codex404
Guess I'll have to tinker around a little with it later today :D.
Last time I checked it wasn't there yet, but as I said, that was a few months ago.

@HisAxelency according to their blog it was added around october 2018

@jurion ? QT works fine on high dpi devices
https://doc.qt.io/qt-5/highdpi.html

Anything with XAML from MS is really good IMHO. This is wpf/uwp/Xamarin.
Only the last one is kinda portable.

Flutter?