Every couple of years I like to replay the Musou Empires games in my eternal quest to figure out which one I like the most. ever since the spinoff series' creation it's always had a very 'one step forward, one step back, and one to the side' approach so it's hard to rank them.
Dynasty Warriors 4: Empires was the first, and it's hard to critique it without comparing it to its successors. One noticeable difference between it and 5:E is how policies are handled. In 4:E you can only choose policies your advisors offer, and you can only choose one option per turn. In 5:E you can either choose your advisors options or choose your own policy, along with eventually being able to perform 5 of them per turn. This makes the game much less frustrating, but also makes it noticeably easier. Another big difference is how items are handled. In 4:E every items takes a certain amount of turns to be produced, and they're automatically added once made. In 5 you need to manually make items individually, which just feels time consuming.
In terms of combat, 5 wins out mainly due to the small changes to combat that happened between DW4 and 5, though neither game lets you individually give orders to officers in the field, which is annoying. 5:E also introduced unit positioning on the strategy map, which was a welcome feature and adds a bit of depth to the planning stage. 4:E, however, did have a much larger variety in endings, and still does out of all the empires games I've played.
With that out of the way we come to my favourite part of the empires games: edit mode! Introduced in DW4, 4:E greatly expands on the relatively primitive feature in most ways. Custom characters can choose anyone's weapon, have different builds, different voices, abilities and you can choose their stats. 5:E expands on this by allowing us to choose different faces, and hairstyles, but oddly enough removes the ability to choose your edit character's stats, which is a shame. 5:E also removes preset body builds and replaced it with a custom body slider, as well as having all clothing/armour pieces available to everyone. One minor annoyance is that your edit characters are always depicted wearing default clothing during dialogue scenes and in game messages, which isn't the case in 4:E. Finally, 4 only lets you make 4 characters despite having 6 body types to choose from, while 5 allows up to 10.
Overall, I'd say I enjoyed 5:E more, but they're both still fun to play. 4:E does have a really fun versus mode though, which has unfortunately not been brought back.