I worked on a derivatives system for a bank where we had a few thousand servers globally running distributed calculations. We chose C# over Java as it was more

I worked on a derivatives system for a bank where we had a few thousand servers globally running distributed calculations. We chose C# over Java as it was more powerful at the time. Windows server was rock solid throughout, it also had the benefit of being integrated with Windows security. Now Linux you can run dotnet applications OK we'd probably choose that because its cheaper not because its better. Most server applications you just need a bare OS and run a process, it doesn't need much.