choice to pick female or male representative of each faction

This would be really cool for most of the factions. Representation is important, and I find myself gravitating towards the female led factions. It'd be a lot of work, the animated portraits are beautiful and I imagine they take a while, but there's something to be said for choice.

I trust Amplitude to handle this tastefully if it is done. I wonder what it would look like for the Cravers, seeing as the Queen is pretty masculine.

I wouldn't want an asexual faction like the Riftborn to have another option. The leader's voice is female, for sure, if we go by our human standards, but an asexual race would have no perception of this.

The Horatio, of course, would have to remain untouched, so there would be the precedent for a faction without the gender option.

It would be interesting, but even for the empire maybe not straight forward. We like to identify ruling class with that old boys network, that is why an old emperor works well. You have to tell less, because the setting speaks for itself. The way things are portrait and are said force us to fill out the blanks. We see very little of an actual empire, but I think we all have a mental picture in our minds. You would need to venture towards a type as queen Elizabeth to get the same vibe (albeit lore wise I think the quests give the option for a daughter to take over).  

Such options need to support the existing archetypes. The setting or vibe should not suffer from it. An insectoid species being led by a queen is instantly relatable as we all know ants. Similarly a new faction with strong female leaders/ warriors where the man look smaller, beautiful or elegant could work well (peacock, lions, spiders). 

For the Lumeris a swap around is logical considering their society, Vodyani works also. Sophons wear helmets and are lead by their AI. Horatio are simply Horatio. Trees and plants have their own set of rules. Riftborn are sexless.

Considering vodyani (only because their suits have distinctive silhouettes) and lumeris you would get a male option added, than only the empire would gain a female option.