My (current) understanding of the intentions:
Internal Sectors: a Kepler, a Comet, maybe a Centaur-B or Miranda-B (maybe we will need more ships in the 5 Federal members space)
Border Zones (quiet): an Excelsior or HC, a Rennie-A, a Kepler, a Comet, maybe a Centaur-B or Miranda-B
Border Zones (busy): add another Rennie and some more frigates
Border Zones (HOT): add another Excelsior or HC, add another Rennie and some more frigates
Task Forces (unopposed): Constellation-A as leader, add ships as appropriate to role.
Task Forces (opposed): Ambassador or Excelsior as leader, add ships as appropriate to role.