Storyboard or xib with large number of view controllers

I have an app with a large number of view controllers (i estimate more then 70 VC) ill probably be building the app with iOS 10 deployment target my question is for this large number of VC are story board recommended or singe Xib file per class ill note that the app will be TDD driven and i need the code as modular as possible.

Thanks for the help.