I liked Argu when writing .NET in the past. Seemed a lot more feature rich and easier to whip something up than the free alternate C# OSS ones at the time - and IMO looking at this for a typical CLI command app probably still is. Argu's advantage over this, at least it seems to me, is there's a lot less boilerplate (more defaults, less annotations, less classes/files). You could write a solid CLI app with subcommands, etc in a single script if you wanted to. Spectre's advantage seems to be if you want to create an interactive CLI application.