I am using StyleCop for a quite a while (and I am used to it). Friend of mine recommended me to also try CodeMaid. First thing I've noticed is difference in usings organisation.

Stylecop orders usings in alphabetical order where System usings are listed first and non-system usings are listed below.

CodeMaid orders usings also in alphabetical order but it does not order System usings first. It only orders usings alphabetically

Another thing I came across is that CodeMaid allows you to have usings outside of namespace (and as far as I know it is better to place all the usings within the namespace)

I wanted to ask what is the proper ordering of usings and eventually why?