The type of love that is generally celebrated on St. Valentines day is what the Greeks called Eros or Romantic love. Valentine, who lived in the 4th century ,over time has become identified with that type of love, though it was his devotion to Agape-Love of God-for which he became well known, suffered martyrdom and became a Saint..
Perhaps, though the best description of love ever written and a wonderful example of the same would be that of Saul of Tarsus, who before his conversion was consumed by murderous hatred. After his conversion, this Apostle of love, Saint Paul- the prime example of Love's transforming power would give the the world these beautiful, enduring words "Love suffers long and is kind, Love does not envy, Is not easily provoked and is not jealous, Does not exalt itself, Seeks not its own- Thinks no evil. Bears all things, believes all things, hopes all things, endures all things. Love never fails"
All loves- Agape(Gods love), Eros(romantic) Philo(friendship) are important and all have their place in a well lived , meaningful life, but as C.S. Lewis says; "Agape by definition is the highest and most unselfish of these loves"