C# also has Linq to Xml and the XDocument et al. classes which are a nice way of reading / writing XML. I personally like XML. It’s a bit on the verbose side,

C# also has Linq to Xml and the XDocument et al. classes which are a nice way of reading / writing XML. I personally like XML. It’s a bit on the verbose side, but that makes is way more easy to figure out the position in the tree than it is in JSON. It is also more easily extensible thanks to attributes and namespaces. It supports comments which is mandatory for any configuration format for obvious reasons. It has powerfull transformation engine as well as schema capabilities. JSON schema keep producing new draft of its spec, yet the result is not on par with XML, and more painful to write. I’d like for XML to make a come back, not as the behemoth it was once, but for case it makes sense, and configuration files is definitely one of those.