-Barack Obama, in a video on his campaign site.
Couldn't find a similar discussion of faith on Clinton's site. Obama seems interested in allowing people to be open about spirituality without being at odds with each other.
I was going to vote for Edwards because of how important environmentalism is to me. After briefly checking out the Obama and Clinton "Issues" pages, it seems to me like Obama is making slightly more realistic promises. He also mentions reducing deforestation, while Clinton only discusses energy and global warming.
I'll vote for whichever in the general election, but I'm leaning slightly towards Obama. He also seems generally more electable, as for whatever reason a lot of people seem to loathe Hillary Clinton.