Joyful. I chose this in high school, when I had a choice of being first in my class, or taking a class that was challenging for me. I chose to take the class, learn more, get a lower grade, and let my friend be first in the class. He had expected it when he was in 9th and 10th grades. I came to the school in 11th grade, and he had competition. It meant more to him than to me. And learning all I could made a lot to me. So we both won.
Being joyful when others are joyful is called "mudita" in the Buddhist tradition. Feeling bitter or bad when others succeed is called "Sour grapes" (from a story by Aesop, The Fox and the Grapes) or, in German Shadenfreund.