If you only watch one anime in your life, make it Death Note . The premise is genius: a brilliant student finds a notebook that kills anyone whose name he writes in it. What follows is a cat-and-mouse game between him (Light) and the world’s greatest detective (L).
When looking for your next fix, consider what you enjoy in other media: Try Berserk or Attack on Titan . If you only watch one anime in your life, make it Death Note