I'm starting S03 and right now my absolute favorite character is Data. But to be honest, Data is often great because of his relationships with and the way all the other crew members interact with and support him.
First and foremost, I love his friendship with Geordi.
Then of course the way specific crew members such as Picard, the doctors (Crusher and Pulaski), and Guinan help him to further his understanding of human behavior is wonderful too. Their tact and warmth in doing so makes me feel good.
What are you favorite characters the first couple seasons, and why is it Data?
Oh yes! That was a very good episode. Riker also had my sympathies, because you could tell it hurt him to be forced to argue against Data's individual sovereignty.