Having a personality is all nice and well but it doesnt explain how she looks like a naked curvy woman with bodypaint.
Fanservice is essentially unnecessary visual content intentionally added in order to please fans.
A holographic semi naked woman is a holographic semi naked woman.
Oh she is definitely fan service, gamers just gloss over the things that they don't want to see like that. It effectively comes down to what games people do and do not like and thus what they are willing to overlook in those games.
And this round has to go to Big Daddy in my eyes because of a) the main character in Bioshock 2 adding motives and the like to the Big Daddies and b) I hated Cortana in Halo 3 because of her tendency to pop up on screen and slow me down when I'm trying to complete the game on Legendary (and have thus already seen that part multiple times before)