This editor (VSCode for short) has supplanted Notepad++ as my editor of choice over the past couple of years. Its cross-platform availability and the increasing number of plugins that broaden its capabilities have made it a must-have both for my corporate laptops (which have been MacBook Pros for both my current and previous employers) and my personal ones. While I haven’t done any development with it (yet), I’ve even found and successfully followed instructions to get VSCode running on a Google Pixelbook.
This Visual Studio plug-in is the only tool that I pay for out of pocket to ensure that I have it regardless of where I’m working. Version 8 was released earlier this year and I’ve been using it since version 3. The features I make the heaviest use of are its test runner, refactorings, and navigation capabilities. But it also offers excellent code generation, static analysis capabilities and a host of additional features that contribute to developing better code more quickly. It is the only tool I’ve ever encountered that taught me new things about features like LINQ, generic interfaces and classes, and concepts like covariance and contravariance. Having used it for years (and memorized keyboard shortcuts for my favorite features), developing without it is a painful and sad experience. If you make your living building .NET applications, I highly recommend purchasing it yourself, whether your employer does or not.
While the primary purpose of LINQPad is to query database with LINQ instead of SQL, I use it far more as a C# scratchpad to test LINQ queries and other small bits of code. I paid for the Premium Edition license, which adds many useful features and makes it comfortable to write small programs in.