I found all of the science sections and the reading section from DAT Genius to be particularly helpful. PAT was too easy compared to the real one, and QR was just okay. If you have time, it would be a good idea to do both as suggested above.
I talked to the director of admissions at one of my top school choices, and after talking to students he has admitted as well as students that were not admitted, he HIGHLY recommended doing DAT Bootcamp, and reinforcing with Qvault. Again, just another person's opinion, but I thought it may be helpful since it came from someone that knows a thing or two about DAT scores!
i used qvault only for biology. it didn't really help much and they phrased things and set their questions up in a different way than on the dat. that being said, there is a lot of useful info on qvault and it has aided many people in addition to bootcamp and destroyer. I'm not that great at bio and got a 19 on the real thing.