I think it is sonnet number 130 (not sure about the number), but it is the one that starts off "My mistress' eyes are nothing like the sun." I take it as a humorous poem about someone praising the beauty of his ugly girlfriend.
I prefer Shakespeare"s plays to his sonnets. I am especially fond of "Tomorrow, tomorrow, and tomorrow creeps in this petty pace from day to day. . . " from Macbeth, my favorite tragedy. If I were to pick a sonnet, it would be #18: "How I compare thee to a summer's day..."