What is the naval equivalent of a main battle tank's firepower, protection, and staying power?
Short answerThere is no close modern escort equivalent; the ship type designed to take heavy hits and continue fighting was the battleship.
NotesA direct anti-ship missile hit can range from mission-killing damage to total loss depending on impact location and follow-on effects. Ordinary escorts are not built to exchange such blows repeatedly. Recreating that expectation would mean building a battleship-sized protective system rather than merely adding modest armour to a frigate. Subdivision, internal protection, and damage control can improve survival and repairability, but they cannot guarantee that the ship remains combat-effective after a major hit.