Any TNG character to Data:
You are not content with being as you are. You desire to become something more like a human, or any organic sentient humanoid. But desire and discontentment are emotions. What makes you think you’re emotionless now? If you were, you would be like the ship’s computer. You would do everything and only what you’re told, and it would never even occur to you to do anything because you want to.
Somebody should have pointed out that fairly obvious point at some point in the series.
OTOH, in “Measure of a Man,” there is a trial to determine whether Data is only property, or a sentient being with civil rights. Riker is assigned to prove he is property and, being Riker, can’t do it without putting hall all into it (which causes him some guilt afterwards). But, the following season, in “Tin Man,” Tam Elbrun, a Betazoid so hypertelepathic that he can hardly stand to be around people, says to Data: “Why, I can’t read you at all! It’s like you’re not even there!” If that’s the case, then Troi would not be able to detect any emotional presence from Data either, making him different from every other life form she has ever encountered; and that probably would be common knowledge on the ship. So it’s something Riker should have used! He should’ve put Troi on the stand! I mean, it raises the possibility that there’s some defining characteristic of “life” which an artificial being, even one of Data’s sophistication, lacks entirely.
Picard, OTOH, considering that he’s trying not just to win the case but to save Data from being dismantled for study, ought to have raised what lawyers call an alternative theory of the case: If Data is property, whose? If Noonien Soong had any surviving relatives, they might have a better claim to ownership than Starfleet has, and his disposition ought to be put on hold until that possibility is settled. At least it would buy him some time.
(I’m a lawyer, BTW.)