At the time I started thinking about making that change, I don't think I had a good answer. I started using Python, and Python Tools for Visual Studio, and thought, this is fucked, because I love this tool, and it's tying me to Windows still, so I consciously made the decision to switch out my dev tool to Komodo. I don't love it. It's got nothing on PTVS, but it runs on Linux really well.

For a decent dev tool under Linux - what about MonoDevelop? VSCode looks ok, but I haven't tried the Linux version, but apparently you can do C# development in it.

I'm not really up to speed with C# dev these days, last job I had which required C# was 2009, and since then I really haven't done much serious development in it (It's 95% Delphi professionally, and Python for my own stuff)

Edit: I wanted to re-iterate, I absolutely love Python Tools for Visual Studio. Those guys have created (what I have found to be) the highest quality python development tool I have experienced. The downside is it requires Visual Studio. If they can take what they have added to VS, and re-produce that in VSCode.... Wow, I would be very happy.

For python, try Pycharm. There's also community edition, which may or may not be enough for you. Another step up is Intellij Idea, which supports everything that all the other language-specific products together.

For a nice Delphi alternative, try Lazarus (http://www.lazarus-ide.org/). Like Delphi 7, but with more features. Documentation could be better though.

Jetbrains IDEs are awesome, you should give them a try. And they are several ways to get them for free : communitiy editions, student editions, beta versions or even if you own a popular Open Source project they'll give you a complete commercial version for free.

I would say IntelliJ in one of its different incarnations (PyCharm, RubyMine, WebStorm, etc.). Of course, it's not specific to Linux, but that's a nice advantage.

If you're willing to switch from c# to something else: python or Java, although for desktop apps it may not be as good (I used to work on PyQt apps and did not found it lacking though.)

As for the IDE Intellij IDEA rocks and has a community edition.

Eclipse or IntelliJ and Java/Groovy. I can't believe I wasn't using Groovy earlier, it's fantastic.

I have the same problem as you and the closest thing i have found is scala and intellij. But I dont really like scala as i find it messy also there is nothing out there that is as good as wpf with mvvm.

Java + NetBeans, IntelliJ, or Eclipse. This isn't the land of Microsoft, you have a choice of IDEs. I happen to prefer NetBeans, though recently I've been turned on to IntelliJ and that's been growing on me. I've never really liked Eclipse. But you know what? That's me. You might have different tastes. What's really nice is if you use Maven to manage your builds, your team members can use whatever IDE they want and everything works together. It's a great world out here!

IntelliJ IDEA + Kotlin. Kotlin is created by JetBrains themselves and is very easy for C# devs to pick up and can be used anywhere Java would be used.

MonoDevelop for .NET stuff (http://www.monodevelop.com/), QtCreator for C/C++ (http://www.qt.io/ide/).

QtCreator and C++ aren't bad. At least you get the designer for laying out your GUI a la VS