I have used both of these curricula.
First, if you are looking for a truly Christian Science curriculum, the Berean Builders is better, hands down. Dr. Wile weaves the Christian, creationist viewpoint into everything.
Sonlight, if you’re talking about the elementary/middle school levels, on the other hand, uses mainly secular books. For example, in the Sonlight Science E program, none of the books are from a Christian perspective. They are all secular (DK, Osborne, etc.). I had to find supplemental Christian books to counter any evolution material that was present in the books. Another thing I didn’t like is the readings felt very choppy and a lot of times the experiments have nothing to do with the concepts being learned. It’s just too disjointed. While it is all laid-out nicely, content-wise it wasn’t aligned with our worldview (even though Sonlight is a Christian company).
My son used Science in the Atomic Age this past year and he loved it. While it may seem textbook-y, it really isn’t.
The way Dr. Wile writes is like he is having a conversation with the student as they go through the book. Also, he emphasizes that the experiments are meant to be viewed as a demonstration of the concepts being learned, not something from which to create an entire lab report (at least with the book we did; this may be different for high school).
I’m not sure what grade levels you’re looking for but Science in the Atomic Age had a schedule to follow and a downloadable & printable notebook for the on-your-own questions and study guide questions. My son did everything pretty independently, including the experiments (he was 8th grade).
Check out Dr. Wile’s blog as well as the Berean Builders site. There’s lots of insight there.
I hope this helped. Let me know if you have additional questions.