In fact, i love the entire album but i have to choice and my favorite song is "Phosphor" ^^.
I enjoy this album because Race To Polaris succeeded to create a dark and futuric ambience in "4909". It really seems to be a soundtrack movie. Every song is dynamic and catchy despite (or thanks ^^) the deep ambience.
I like 4909 and I'm going to listen his prequel "Breakneck City".