Using LabVIEW code in c#

Hi could you please let me know how is the best way of using LabVIEW code in c#. I see there are 2 options , making a dll or ,NET interop. Could you please let me know which one is better

I also have another question. when I want to make a dll or .NET I need to add my source VIs. I haev used many SubVIs to my main vi. Do I need to add all the SubVIs to Exported VIs or I need add my SubVIs to Always Included?

Thanks