Ten years ago I stepped away from the Microsoft ecosystem, in large part due to said ecosystem drifting away from industry best practices at the time, and also a conservative development culture formed around this ecosystem that did not want to acknowledge the outside world. So if I were starting a new project eight years ago, .NET would've been one of the last technologies I would've picked, despite big love for C#.

When I was starting a new project a couple of years back, I went with .NET 6 and never looked back. The Core branch (and subsequent versions) fixed a lot of the issues I had with the original .NET Framework. Happily developing with VSCode on a Mac and deploying to ARM-based Linux instances in AWS. To the original question, the only right answer is you should pick what you know unless there is some overriding reason (e.g. performance). When building a backend API, I'd personally pick C# over JS all day.