I have a separate post about units here Suggestions On Units Balance And Gameplay - Age of Empires IV - Age of Empires Forum
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I think they are fun and easy to pick up and use, my elementary school younger sibling took great joy in using them and had a much easier time playing them than the other civs.
they do feel oppressive when played well though and I would like for council hall to be slightly reworked. maybe it should have a 25% discount on longbow upgrades and a 50% production bonus, increased to 100% when under the influence of “network of castles”?
the abbey feels real bad, maybe make it a church that can train monks, research upgrades and hold relics in age 3? the castle landmarks also feels underwhelming, though that maybe castles in general.
Holy Roman Empire
the prelate feels amazing, the 40% carry capacity is a massive bonus, the wonders feel impactful except for the barracks and last castle landmark. maybe a 20% discount for the infantry batches?
its fun, feels different but still easy to play, and a good civ. just slightly buggy.
Chinese
the tax collector feels useless, especially compared to the prelate. the dynasties are too expensive, the units they give are underwhelming, the wonders are easily the worst, and nothing about them made me want to play them more. their unique mechanics feel too cumbersome to utilize and not very rewarding.
they somehow feel more bland and uninteresting than any other civ despite being able to make all landmarks and the most unique units/bonuses. the only truly “bad” civ in the beta and the only ones I think are in need of changes to their core gameplay.
Abbasid
Feels balanced, lots of options, fun, but hard to play to full potential. downside is that they have no control over the speed of aging up and some upgrades in the house of wisdom feel way more impactful than others. maybe give phalanx upgrade an additional bonus vs cav? bonus speed for infantry support?
their golden age mechanic requirements needs to be looked at, maybe change it to 15-30-45 from 10-30-60? it feels like it kicks in too fast and requires an absurd amount of buildings for the final level.
their water sucks too.
Overall
I think all the civs I have played aside from the Chinese are in pretty good shape, and I cant wait to play them more. each one feels different enough from the other while being relatively easy and fun to play. they offer unique and distinct gameplay that is also enjoyable and enticing, so good job.