Lynn,
I agree about Sam. He was my pick several chapters ago. But I suspect we have a number of misdirections to go through first :

.
Of course there is always option three and DC could always get rid of the annoying Ellen. I have always been amazed why more authors do not kill Ellen off in these stories. Sam makes the most sense to me because he feels like he let Lois down when she was young and this might be his opportunity to make it up to her.
Like I have said before, Clark is so obvious that I am pretty sure he is safe.
Mike