In "Chain of Command II," Captain Jellico tries to recruit pilots for a dangerous mission against the Cardassians. Geordi tells him that Commander Riker is the best shuttle pilot onboard. What about Data, though? I don't understand how a human being could possibly be better than an android of Data's skills at flying a spacecraft.
Data is a competent pilot, but he's too risk-averse to be a great pilot. As he says in "Nemesis":
It's the difference between trusting the autopilot and flying it yourself.
We also see that although his knowledge of piloting is extensive, it doesn't match that of an experienced ship's pilot like Picard in TNG : Booby Trap. Data doesn't spot that Picard is creating a slingshot effect.
To elaborate on a point in Richard's fine answer, it's a very common conceit in science fiction, when introducing androids that are, from a technical standpoint superior to humans in every way, to focus on the intrinsic advantages that humans have over them, usually couched in semi-mystic terminology like "spirit" or "innovative essence" or "intuition".
This is a common answer to many "what good are the humans?" questions, and here as well - Data's reflexes and spacial perception may be superior, but when you define good piloting as a combination of technical ability with aforementioned human recklessness and ingenuity, an android can't match.