I _highly_ recommend [VSCodium](https://vscodium.com/) if you are on Windows or OSX, and Code - OSS if you are on Linux. These are free-software distributions of Microsoft's VSCode editor, which features excellent C# integration and various convenient features, like an integrated Git interface and terminal. (Make sure you set the terminal to Git Bash if you are on Windows - this is under File -> Settings.)
Of course, if you prefer some other editor, that will be perfectly fine. Visual Studio is a popular choice for Windows that features good performance measuring tools, and many people sing the praises of [JetBrains Rider](https://www.jetbrains.com/rider/).
