I hesitate to say this here, but it has to be done: Lucky Star is, singlehandedly, the greatest literary work ever composed.
The intricate storylines and the all-too-human characters appeal directly into our hearts at the deepest level--the trials faced by the girls represent the daily hardships that face us all in the present, poor Kagami~n's efforts in love are recognizable as memories in our own past, and Konata's sheer strength of character is something that we ALL should strive to match in our futures.
Truly, a work of art that you will find your self re-watching time and time again. Even then, you will be clamoring for more. LUCKY STAR for LIFE!