Keep her
I feel like she has a little more to offer because she is a sympathic character. The majority of her time in the MCU has been spent consistently having everything taken from her with no real break or levity.
More than heroic or villianous, shes tragic. Theres far more motivation to her heel turn than an ego driven need for control, dominate, or eradicate.
Plus, if you're bringing in mutants she has a lot to offer their story and introduction especially since since shes well established.
And dont they still have plans for Vision?