For me, it would be:
- removal of 'root' user and replaced with various predefined sysadmin groups and standardized audit logs for each group
- get a batch processing system (similar in spirit to z/OS but without JCL). It should allow you to see a list of the jobs you've submitted, cancel individual jobs, re-order existing jobs that haven't started, have a standard place to see stdout/stderr logs.
- get something like AIX's smit/smitty for sysadmin tasks
- have either ZFS built-in or something with equivalent functionality
- sensible and easy-to-use containerized/jailing capabilities
- built-in support for append-only file permissions
- ability to quickly/easily adjust priorities for all processes belonging to a user
- ability to quickly/easily cap a user's processes cpu/ram resources (without having to use a container/jail)