I love the Knight, then the pawn. I love the Knight because the piece itself is a constant reminder to think ahead. Since Knight moves often require two, three, and four moves to get places, you have to think ahead.
As for the pawn, the pawn is like the common sparrow. Most people look at the sparrow and see a dirty little bird. However, these birds exist where other birds would simple die out. Like the sparrow, the pawn is a tough little piece. God help you when your opponent's pawn gets to the other side of the board.
What's your favorite chess piece and why?
Mine is the pawn. There is no turning back for this piece. It can either stay put or advance toward the enemy camp. And its reward for reaching the opposite border is promotion to the strongest piece!