Epic is pretty much Legacy, I think some tweaks were made to the engine/script, but sounds are from Legacy.
Compared to One, its more organic, has better separation between players (which I assume comes from smaller orchestra and /or closer micing), its attack is gradual (so more symphonic like) where as One is more like Ark 1 (127 from the get go).
One also doesn't have the dynamic range of Epic/Legacy, its really like Ark 1, no soft layer at all.
All that doesn't mean that one (for lack of better word) is better than the other, they are simply different animals.
What I think most ppl are more aware of at first listen and don't like in One is the default mic, the tree, which for some reason (or reasons: bigger orchestra, mic position,
mic type, reflectors positions... or lack of) contribute to a sound that is very homogeneous, you don't really hear the players... so it gives a feel like its a bit like a pad (what ppl call processed), which is something you can't fix with an eq.
On the other hand the other mics are fine, you can blend in the close mic with the tree, or ditch the tree totally and use close and ambient and outriggers to get the "players" back into the "orchestra"
That won't change the dna of One, which is actually way more epic then Epic