The scenario presented for the question:
(i). Revoking an individual's access rights to a particular set of files, but not all files
(ii). Revoking access to a particular file from a group of users, but not all users.
Answer:
(i). Capability List would be a better choice
(ii). Access Control List (acl) would be a better choice.
Explanation:
(i). Revoking an individual's access rights to a particular set of files, but not all files
A capability list is a better choice here. All one needs to do is go to the individual's capability and remove the capability that gives the individual rights over those particular set of files one wants to revoke. This would not be possible for acl, as one would need to go to each file in the particular set of file to be revoked, confirm if the individual has a right for each file and then revoke. This process will take more time.
(ii). Revoking access to a particular file from a group of users, but not all users.
Access Control List (acl) would be a better choice because one can simply access the particular file acl and revoke the rights of the group of users they intend to.This is not the case for capability list, as one would need to confirm from the capability list of each user to know if they have access to the particular file and revoke their access. This will take more time.