That's a tough one, but I probably wouldn't listen to either of them with a girl.... well.. It depends on the girl, if she was really into Opeth (wow, that's a dreamgirl for me), then probably Credence.. But if she wasn't very familiar with the band, it may seem awkward to her. I dunno. I'm not a girl... And not all girls think alike... So this opinion is not very well backed up. Don't listen to me...
I know I like Harvest better as a song though. I love Harvest. In some previous threads I've actually seen it put down some.. I don't know why, I think it's a beautiful song. It may be a lot different from their other work, but at least they're trying new things..