I believe love is stronger than anger for several reasons. First love makes you happy and lighthearted, while anger can eat you alive from the inside out. Love and easier emotion than anger, kind of like the smile in the frown, it takes more muscles to from than to smile.
If you are referring to love and anger in a marriage, it is always hard, almost impossible to stay angry with someone you truly love. When referring to a friendship, love is always needed and accepted, whereas if you get angry at your friend, if you do not realize the LOVE you have for them , well, the friendship could very well end. Leaving you more angry.
Love is the most important emotion there is. Love of mankind, love of your family, love of your friends, nature, your pets and so on. Could you imagine a life filled with nothing but anger? What a lonely life that would be.