As for me, I prefer "Ab Initio" by far (and not necessarily because of Vibeke, who's already great). In my opinion, it has such a wonderful atmosphere, very beautiful lyrics and the music itself is just fabulous. It feels like "some kind of heaven" everytime I listen to it. I've heard "In the wake" as well, but it gets to be the opposite of "Ab Initio" for me. I think that it actually has some interesting tunes and musical variations, but I don't like the song at all.
Sadly, it's got impossible for me to get neither an Illumination edition with "Ab Initio" on it (since I live in Europe) nor the "Sanguine Sky" single, although I would even say that it's my favourite song on Illumination (talking overall).
Greetings and my best wishes to everyone, it's a pleasure to be on this board!