John Legend might be the next "Stevie Wonder" of the 21st Century, and for very good reasons.
One, he knows how to write a good song, and each of them turns up to be original R&B song.
Second, his voice is sad yet soulful to anyone who listens to them, and it has a very good beat to it.
Finally, he is talented when it comes with his own piano, which help to coordinate the song he is playing.
So, if you want a song to cheer up, I suggest an album from Legend.