I just talked with a WordPress developer yesterday, and he said Dreamhost has trouble in security. Not sure if it's still there, cause he used Dreamhost few months ago.
BTW, why do you want to choose those hosts? If you just need PHP, mySQL, there are multiple good vendors out there. Any other consider factors? Such as location, price, space, bandwidth. Or what are you going to host with that account? If you can show more details, we can direct you to a correct vendor.