What was your favorite year he played?
That is hard to say.  He was pretty consistent throughout his career. I can't recall of him being out for any length of time.
Mine was 2010 when he was award the Defensive Player of the year.  Do you have a favorite play?
I loved to watch him jump over the offensive line to get to the quarterback.  Seemed he did that more than once
That's a classic football play, when you get over the offensive line and tackle the QB.
The other play that I remember most was his pick against Flacco to ice the game in the AFC championship game.
Nice, always great to put up the game winner in a game like that.  Why do you think he was so good?  I know he was into surfing which probably helped to develop a good sense of balance.  He also like playing piano and making furniture which maybe helped him to focus his mind and stay sharp.
I think he had exceptional reflexes and speed, but even more important I thing he was smart and could see where the play was going.
Definitely be able to get a good read in a fast paced game of people with incredible ability.
He was a once in a lifetime safety.