The drop-down menu currently always includes potentially irrelevant (unplayable) civilisations.
With 56 total civs (soon to be 59), it may not seem much to filter down to 53 from 59, but I think it will be worthwhile because browsing 53 civs in a single dropdown menu is staggering enough without having an additional 6 in the list which are completely irrelevant because you cannot play eg. Puru in ranked.
Let the player filter out which civs are displayed in the dropdown menu. At least regarding which civs are actually playable in the current context (let them filter out Chronicles civs). Additional filter capabilities (like per DLC) would be a plus but not as important as filtering out Spartans and what-not.
Illustration of what I’m suggesting:
