I read the lot. (Ordered quite a few thru the library) Big mistake. One book explaining attachment theory is quite enough - you don't need the same thing explaining again and again. (It is very important obvs but a lot of the experts are on the same page) Post the list and we can help you pick the best ones in each "category".
I'm less sure about Sally Donovan, while she has a lot of expertise borne out of very difficult adoption experience, she writes on the premise that everyone will have an equally challenging placement. If I'd read her first I would have felt very daunted and unsure that I could develop the parenting skills needed. While I know some folk do have that kind of challenge, many don't and you could get quite a skewed idea about the children you're likely to be placed with.