As much as I love the purple I feel its too dark to have light come into view for the cover of a book in such as it is in this picture. But the end result will always be yours. Good luck with which ever you choose.
Cover A is too dark, and while I'm not personally a fan of yellow, I would pick up this book in yellow first because I can SEE the design in it, while the other one for me runs together and is hard to differentiate because it is so dark. Your picture is a little larger in B, as well, and that always helps.
Cover A was too dramatic for this journey.
Cover B speaks to me for enlightenment.