Well that depends on:
If you don't have to worry about money then I think you should purchase the online portion. I felt going to classes are useless and you can use those time to study on your own. I liked the online portion because it allows you to do many problems. I bought both Kaplan stuff and DAT destroyer and sometimes they overlap each other but there is some variety of questions you can encounter by having both.
If you are worried about money, then I suggest DAT destroyer, Crack PAT, topscore, Cliff AP, etc. I took the DAT recently and I just felt the Biology section was just so random. As I am not a bio-major (I am engineer) and I haven't encountered some of the experiment that they had questions on. But DAT destroyer prepares you really well for chem and ochem section.
Good luck