Hi Joseph,
I have to agree, "Little god of my heart" is the strongest ending.
There is a very lugubrious feeling to it, you just can feel death is near.
It is the only one that has the right feel to it for the situation.
The first one, sacred bird, is a reprise of "I'd give my life for you" which is just too obvious and does not quite convey the right feel. The newest one sounds more like an "entr'acte" to me, a bit too happy as well, it conveys a feel of excitement.
Here is a clip of all 3 endings:
http://www.youtube.com/watch?v=rzGfBDvHPeo