I can tell you that Achiever (along with Barron's) was very helpful for the PAT and the reading sections - it provided good simulated practice for both of those sections. However, I used the Destroyer for my sciences - it is unparalleled in its ability to boost your science scores. So if you want to have a well rounded score in all sections, I would say use both. But if the sciences are your weak point or you just want to be totally prepared for any science question on the DAT, Destroyer is definitely the way to go. Good luck!!!