Current CG characters look horrible and fake. If a true AI wants to use a human facade to better relate to people, I think it would get the details of facial expressions right, not create another rubber-lipped video game character. So the AI's stand in would be indistinguishable from a person.
Personally, I think CGI characters are getting better and better in movies.
there's an AI character who appears as a hologram to interact with the main character.
I understand there is an intention to separate the human actors/actresses in the appearance of a technologically advanced scenario.
If the hologram looks and reacts with the set the same as the other actors, it will be hard to tell the difference unless you paste a "H" on her head.
No offense, Rimmer
For the viewer to associate that actress with being a hologram, something needs to be different.
The question is, should the hologram be 'played' by an actress or a CGI construct?
I think it entirely depends on what the filmmaker wants the 'hologram' to do.
One must ask the question while watching the film if the technology is advanced enough to make indistinguishable holographic humans.
If the technology doesn't match up with what is portrayed in the film, the viewer might have a problem suspending their disbelief.
So, one consideration that might be given is how 'other' holographic constructs look.
Will there be holographic displays?
A holographic apple being bitten?
A chunky big head avatar being shown?
How much CGI and how detailed it will be will determine whether an AI character who appears as a hologram to interact with the main character will be more believable as a CGI construct or an actress.
I think there was a LOTR film done in the 70s or 80s that used actual actors with colorizing effects to make them fit in with the cartoon elements.
I think it was this one...
Publicity for the film announced that Bakshi had created "the first movie painting" by utilizing "an entirely new technique in filmmaking." Much of the film used live-action footage which was then rotoscoped to produce an animated look. This saved production costs and gave the animated characters a more realistic look.
~ Wiki
The point is, the filmmaker took steps so the 'look' matched.