THE FOLLOWING IS RAMIL'S CODE TO ADD FEATURED MEMBERS AS A FILTER CRITERIA
 
In your Includes folder OPEN: cp.members.php
 
FIND: $_GET['status'] == "0"
 
On the same line AFTER "0" ADD: || $_GET['status'] == "3"
 
NOTE: you have to add || $_GET['status'] == "3" after every instance of $_GET['status'] == "0". For version 2.5.3 there were five $_GET['status'] == "0" in cp.members.php.
 

 
FIND: $wherestatus = $status == 0 ? "m.active='0'" : $wherestatus;
 
ADD ON NEXT LINE: $wherestatus = $status == 3 ? "m.featured='1'" : $wherestatus;
 
FIND: $status_box['0'] = ($LANG['members']['inactive']);
 
ADD ON NEXT LINE: $status_box['3'] = "Featured";
 
Thanks Ramil for the code