Like UndergradGuy7 said, people have definitely asked this before. I've found that the posts that say "DAT Done (insert date)" are really useful when considering materials, because you see what people used and how they used them.
That being said, it's a general consensus that Kaplan is NOT enough if you want to be sure and get a 20 or above. There are people who get a 20+ off just Kaplan, but I chose to save my money elsewhere. Here's what is usually considered standard for each section:
Bio - Cliffs AP Bio + Kaplan Blue book. If you want to go to the source, the ADA said that they used Biology 8th edition by Campbell and Biology 8th edition by Raven, but these are both big textbooks
GChem - Chad's videos at Coursesaver.com
OChem - Chad's videos at Coursesaver.com
PAT - Crack the DAT PAT software (google it)
Math - Crack the DAT Math and Math Destroyer.
After you have reviewed all basics, then DAT destroyer has really good practice problems.