I'm having trouble with deciding on this question. With an engineer character who essentially makes sure all the ship's A.I. systems (integrated or free-roaming) to function properly, the character itself could end up becoming more like an NPC to the engineer than an individual role. What made Data so special in Star Trek was that he was capable of learning and then adapting due to the sum of his experiences. As a result, in the Star Trek universe, he was considered an incredible anomaly as far as A.I. went. Story-wise, or at least how we are starting to envision the direction of how things function in this futuristic universe, I worry that an android simply would not be able to function on its own.

Now, I would be completely ok with a cyborg. Take a human and throw in robot parts, sure. But I'm inclined to say no to the android.