Which Batgirl do you wanna see in the DCEU ?

None. Oracle can be in it but not as Batgirl.

i think Cassandra Cain would be interesting as Batgirl.

She actually fits in the DCEU, considering how dark her past is.

I hope the DCEU is rebooted by time we get around to the C-listers.
But if there is one, Kane as Batwoman.

Oracle would be best served in a Birds of Prey movie and/ or Suicide Squad sequel. I totally agree that Cassandra Cain would be the best candidate for the first Batgirl movie. Lady Shiva, Mother, David Cain and the League of Assassins would be the best villains for the first run. In fact, here is a transition that could flow very well. The first Batgirl movie would have the Killing Joke as a story line reference.The second Batgirl would be Cassandra Cain's story and the settings would take place in Gotham as well as places in Europe, Asia and Africa. The final Batgirl movie would be Stephanie Brown's run. Cassandra Cain has killed her actual mother like she did in the comics but has chosen not to spare her with the Lazarus Pit. Cassandra has inherited her mother's title as Lady Shiva and commands her own sect of the League of Assassins. Cassandra passes the mantle onto her only friend Stephanie. Stephanie teams up with Tim Drake and Oracle to save Gotham.