AnoHana is the best drama ever. Also worth a look might be True Tears, Angel Beats, Yahari ore no seishun love comedy wa machigatteiru (the one I just finished), Clannad, Aoi Hana, Myself;Yourself, ReLife, Isshuukan Friends and Your Lie in April.
Also like a million others that I'm forgetting to mention or haven't seen yet probably lol.