Best practice - run Collection or Case Folder Source discovery on PSTs

I have a number of PSTs that I need to bring into Clearwell.  They are all within one folder structure, with a root folder, then subfolders for each custodian and their PSTs contained within.  Can I have opinions on the best practice to bring them into Clearwell?

Either:

a) Run a collection task pointing to the share/folder where the PSTs are located;

or

b) Run a Case Folder Source discovery pointing to the share/folder where the PSTs are located.

Thanks!