What layout should I choose for my NuGet repository?

Artifactory is agnostic to the layout when indexing NuGet packages.
This means that you can use any kind of layout (including Maven layout) and Artifactory will still be able to index and answer the various NuGet API queries from VS or other NuGet compatible tools.

Having said that, please note that it's the client responsibility to deploy to the appropriate layout coordinates. For example if you choose to use Maven layout you'll have to configure your client to deploy the files with a path and a name that adheres to the configured layout.

For more details and an example of publishing from the command line take a look at the Local Repository Layout section on our NuGet wiki page.