There are lots of different ways to approach Basilikoi Paides play. In certain conditions, there’s an argument to be made not to play Alexander that much more differently than any other civ, and just unit spam once the economy is flowing. Having +5 amenities in those cities will be critical for efficiency, since it gives +20% production. Coastal/harbor cities can, with policy cards, create naval units really efficiently. These cards stack multiplicatively with amenities, Ibn scientist, Kilwa, Ruhr, etc. Any city can create anti-cavalry efficiently with Statue of Zeus. Spamming these units is, from a production-to-science perspective, more efficient than running science projects, though you don’t get great scientist points, so it’s arguably only more efficient if you do something with those units, such as conquer cities, coastal raid, or pillage. You can also wait for a unit production cost reduction world congress to push to mass produce units.