I like them both. Obviously "Happy" is taking off faster and is bound to be a much bigger hit than "The Man," but that will still be huge come March/April.
I heard this song in the common room at school the other day and then my friends started singing it today and it's been stuck in my head all day and I'm addicted now. Hope this smashes when it's released in the UK in 2 days, I've already pre-ordered.