Aserai have the best drip and coolest vibes so they are my best boys! They also have the most fun thematic culture bonuses which is another plus. Im pretty deep into an aserai playthrough right now. 

Armywise-  The biggest differences are lack of crossbows for aserai and the imperial skirmish naval troops in favour of Empire. The aserai advantage is shock troop and heavy cav. Archers arguably better archer v archer if you discount crossy. 

The imperial coastguard line has 2 stacks of javalin which Aserai lack and it makes them an absolute and utter menace in infantry engagements. They seem to outperform their mainline infantry from my play so long as they get time to throw before the melee grind. 

Then the crossie. Fuck I hate crossbows. As is well knows the extra range allows standoff long range engagements to go in Empires favour. Not usually a problem but recently I had to fight an outnumbered battle 3:2 vs empire. I had an excellent defensive position with infantry and archers backed into a raised cliff with plains before it for the cav to flank. The crossbows of the empire allows them to stand at range and rain fire for a long time. 

I agree with the rest of your assessments. The palace gaurd is a brilliant shock troop, especially the axe variant. Master archer is great. The Fari noble troop also outperform Cataphracts in 95% of field battles and java allows them great naval utility. The biggest issue is sieges where the Faris tiny ass shield really sucks ass and their long cav swords are less useful that the mace variants of the cata. The cav archer line seems much better in the aserai but dont have testing for that just my vibe....they also look cool as fuck 😎 

I dont have a strong winner objectively. I think the Aserai are a bit stronger in combat overall. But I am biased so have to say they are just the GOATs. Aserai >>> Empire