Imperator Knoedel
Currently obsessed with The Owl House
Personally I always like to have at least two dedicated military cities by the endgame, one with West Point + Heroic Epic and another with Red Cross. Ideally both would be coastal but not too coastal, that is having a rather small number of sea tiles so they can also build ships but otherwise lots of productive land to actually get stuff done in a reasonable amount of time. Both should have a military academy and at least one settled Great General. Beyond that I attach them to units or if I capture an AI city with lots of settled GGs I will build a military academy there for yet another military city.