As a CoH 1 player, one of the best features in that game was the individual count per unit and you start to make a special connection with that unit that killed the most. Thats pretty cool and it was very common to have a hero who killed a lot more people in the past in real life. So honestely having that addition in AoE 4 would be a plus and looking who had that hero in final stats after a match would be amazing.
Well I want to share some thoughts about things devs can add to the game to make it better, even in a rush like the actual state of the game. But these little changes can make the game beloved and unforgettable. Hope the following contribution is useful. 
For example the building collapsing from CoH 3 was way better than we have seen in the shared footage of AoE 4, that would be a good addition. So the exact part that gets hit by a heavy weapon gets destroyed by little parts, like the CoH 3 animations.
Trebouchet and some other siege units need more noticiable rocks to understand better what is going on in screen, also would be nice to see and feel those rock hits on the buildings and walls, and it should be intituibe like in COH 3 and AoE 3, the part that gets wreck usually falls down making it looks amazing.
(look how detailed and contrasted is the cannon ball that we can see it very well and difference from other units)
There is other thing I personally consider annoying and is not having a crew on siege, and it is not only me, all videos about siege weapons got that kind of comment asking for crew on them. Lets watch this beautiful animation and quality shared by forgotten empires in the latest african expansion in AoE 3. That would be great if like in AoE 3, cavalry gets bonification against siege by killing the operators then we see an abandoned siege that can be either captured or just will stay there on the ground to intteract with the physics, terrain or units making the game more enjoyable.
That animation is trully beautiful and full of love and make the game feel alive…
Talking about life, something I really miss to see in the shared footage from the xbox and official AoE site is the squad animations… For example the celebration from AoE 3. Or the chest breathing and involuntary movements from the armies while waiting in the ground. Please devs add those little details that makes the game feel alive. Would be nice to see that visual breathing (smoke effect kind) too from cavalry or units to make us think they are there for real, dealing with cold or fog…
I would like to see some terrain destruction and physics or interaction with the fights. In company 1 if a morter impact the field then it makes a hole and vehicles get affected by that. I would like to see that happening with the terrain in AoE 4.
Other thing I am missing from the shared footage is the units blowing up after a cannon ball hit. That makes the game funnier and more enjoyable too. I wanna see soldiers flying in the air after getting impacted by heavy guns or getting charged by cavalry. (with some logic of course, like in AoE 3)
I would also expect some more details in armor suits and units looking, to difference the units better and have a better feeling after upgrading them.
Again just look the level of detail in AoE 3…
What about Gaia? devs you can still add ducks, birds, tribes, bridges, abandoned props and some other mother nature fauna to make the scenarios beloved (like in AoE 3). I really miss that flock of birds crossing the skies in the middle of the battle, it is so authentic and unic from all the AoE, from AoE 1 to AoE 3.
And to end this little post I could talk a lot more about naval…but its to late to do some significative changes. I would like to see some crew on them firing instead of magic? or that interactive destruction seen in AoE 3 as well as better animations overall but well, I understand the devs are against time so better not talking about that considering the circunstances.
In conclusion please add more animations, gaia and little detailes that makes it feel as a real battle field… This game is so promising and can be enhanced with no doubt, I would appreciate if you can take of this recomendations and add to the game, would love to have an actual developer opinion on this matter.