Which ACL permission should you grant the user while following least privilege practices?

Least privilege would have you grant an ordinary (unprivileged user) the rights to create, read, edit, delete, and execute programs they create. You would restrict the rights in the ACL to other files to no more than read and/or execute for all other files. In many cases you would want to deny one or both of those rights for files that the user does not need to read or does not need to execute. A user may have need to read a text file. A user may have need to execute an application. They should never need to edit or delete files that are not their own. The user should, at most, have the right to grant other users access to files that they own - thus modifying the ACL, but they should not otherwise have access to the ACL.