DBA - Grants

Run this as sys or system to list all grants for users and/or roles, while filtering out all "standard" grants.
Change the where clause(s) where needed.

with users_roles_apex as
( -- all standard Apex users & roles
  select username
  from sys.dba_users
  where username in ('FLOWS_FILES')
  or    username like 'APEX\_%' escape '\' --'
  or    username like 'ORDS\_%' escape '\' --'
  union all
  select role
  from sys.dba_roles
  where role like 'APEX\_%' escape '\' --'
)
, users_roles_db as
( -- all standard Oracle users  & roles
  select username
  from sys.dba_users
  where username in
    ( -- List of standard users - source: http://www.morganslibrary.org/reference/users.html
      -- For database 12c or higher, you can simply use: where oracle_maintained = 'Y'
       'ANONYMOUS','APPQOSSYS','AUDSYS','CTXSYS','DBSFWUSER','DBSNMP','DIP','DVF','DVSYS','GGSYS','GSMADMIN_INTERNAL','GSMCATUSER','GSMUSER','LBACSYS','MDDATA'
      ,'MDSYS','OJVMSYS','OLAPSYS','ORACLE_OCM','ORDDATA','ORDPLUGINS','ORDSYS','OUTLN','PDBADMIN','PM','REMOTE_SCHEDULER_AGENT','SH','SI_INFORMTN_SCHEMA'
      ,'SPATIAL_CSW_ADMIN_USR','SYS','SYS$UMF','SYSBACKUP','SYSDG','SYSKM','SYSRAC','SYSTEM','WMSYS','XDB','XS$NULL'
      -- plus some that were not in the list
      ,'HR'
    )
  union all
  select role as username
  from sys.dba_roles
  where role in
    ( -- List of standard roles - source: http://www.morganslibrary.org/reference/roles.html
      -- For database 12c or higher, you can simply use: where oracle_maintained = 'Y'
       'ADM_PARALLEL_EXECUTE_TASK','APPLICATION_TRACE_VIEWER','AQ_ADMINISTRATOR_ROLE','AQ_USER_ROLE','AUDIT_ADMIN','AUDIT_VIEWER','AUTHENTICATEDUSER'
      ,'CAPTURE_ADMIN','CDB_DBA','CONNECT','CSW_USR_ROLE','CTXAPP','DATAPATCH_ROLE','DATAPUMP_EXP_FULL_DATABASE','DATAPUMP_IMP_FULL_DATABASE','DBA','DBFS_ROLE'
      ,'DBJAVASCRIPT','DBMS_MDX_INTERNAL','DV_ACCTMGR','DV_ADMIN','DV_AUDIT_CLEANUP','DV_DATAPUMP_NETWORK_LINK','DV_GOLDENGATE_ADMIN','DV_GOLDENGATE_REDO_ACCESS'
      ,'DV_MONITOR','DV_OWNER','DV_PATCH_ADMIN','DV_POLICY_OWNER','DV_PUBLIC','DV_REALM_OWNER','DV_REALM_RESOURCE','DV_SECANALYST','DV_STREAMS_ADMIN'
      ,'DV_XSTREAM_ADMIN','EJBCLIENT','EM_EXPRESS_ALL','EM_EXPRESS_BASIC','EXECUTE_CATALOG_ROLE','EXP_FULL_DATABASE','GATHER_SYSTEM_STATISTICS','GDS_CATALOG_SELECT'
      ,'GGSYS_ROLE','GLOBAL_AQ_USER_ROLE','GSMADMIN_ROLE','GSMUSER_ROLE','GSM_POOLADMIN_ROLE','HS_ADMIN_EXECUTE_ROLE','HS_ADMIN_ROLE','HS_ADMIN_SELECT_ROLE'
      ,'IMP_FULL_DATABASE','JAVADEBUGPRIV','JAVAIDPRIV','JAVASYSPRIV','JAVAUSERPRIV','JAVA_ADMIN','JAVA_DEPLOY','JMXSERVER','LBAC_DBA','LOGSTDBY_ADMINISTRATOR'
      ,'OEM_ADVISOR','OEM_MONITOR','OLAP_DBA','OLAP_USER','OLAP_XS_ADMIN','OPTIMIZER_PROCESSING_RATE','ORDADMIN','PDB_DBA','PLUSTRACE','PROVISIONER','PUBLIC'
      ,'RDFCTX_ADMIN','RECOVERY_CATALOG_OWNER','RECOVERY_CATALOG_OWNER_VPD','RECOVERY_CATALOG_USER','RESOURCE','SCHEDULER_ADMIN','SELECT_CATALOG_ROLE','SODA_APP'
      ,'SYSUMF_ROLE','TKPROFER','WM_ADMIN_ROLE','XDBADMIN','XDB_SET_INVOKER','XDB_WEBSERVICES','XDB_WEBSERVICES_OVER_HTTP','XDB_WEBSERVICES_WITH_PUBLIC'
      ,'XFILES_ADMINISTRATOR','XFILES_USER','XS_CACHE_ADMIN','XS_CONNECT','XS_NAMESPACE_ADMIN','XS_SESSION_ADMIN'
      -- plus some that were not in the list
      ,'DELETE_CATALOG_ROLE'
    )
)
select owner
,      grantee
,         'grant ' || lower(privilege)
       || ' on "' || owner || '"."' || table_name
       || '" to "' || grantee || '"'
       || decode(grantable, 'YES', ' with grant option', NULL)
       || ';'
       as sql_statement
from sys.dba_tab_privs
where not ( owner in ( select username from users_roles_apex ) and grantee in ( select username from users_roles_apex ) ) -- ignore "apex -> apex"
and   not ( owner in ( select username from users_roles_apex ) and grantee in ( select username from users_roles_db   ) ) -- ignore "apex -> database"
and   not ( owner in ( select username from users_roles_apex ) and grantee in ( 'PUBLIC', 'ANONYMOUS'                 ) ) -- ignore "apex -> public/anonymous"
and   not ( owner in ( select username from users_roles_db   ) and grantee in ( select username from users_roles_db   ) ) -- ignore "database -> database"
and   not ( owner in ( select username from users_roles_db   ) and grantee in ( select username from users_roles_apex ) ) -- ignore "database -> apex"
and   not ( owner in ( select username from users_roles_db   ) and grantee in ( 'PUBLIC'                        ) )       -- ignore "database -> public"
and     table_name not like 'OLD\_%' escape '\'                                                                     -- '  -- ignore "old" objects
and     table_name not like 'BIN$%'                                                                                       -- ignore "garbage bin" objects
and not (owner = 'SYS'      and table_name in (select directory_name from all_directories))                               -- ignore directories
and not (owner = 'SYS'      and table_name like 'QT%_BUFFER')                                                             -- ignore queue tables
order by owner
,        grantee
,        sql_statement

Run this as any user to list all (filtered) grants.
Change the where clause where needed:

select owner
,      grantee
,         'grant ' || lower(privilege)
       || ' on "' || owner || '"."' || table_name
       || '" to "' || grantee || '"'
       || decode(grantable, 'YES', ' with grant option', NULL)
       || ';'
       as sql_statement
from user_tab_privs
where table_name not like 'OLD\_%' escape '\'                                     --'  -- ignore "old" objects
and   table_name not like 'BIN$%'                                                      -- ignore "garbage bin" objects
and not (owner = 'SYS' and table_name like 'QT%_BUFFER')                               -- ignore queue tables
and not (owner = 'SYS' and table_name in (select directory_name from all_directories)) -- ignore directories
order by owner
,        grantee
,        sql_statement

Privileges (for all non-standard users and roles)

Privileges (for a user)