A proper choice of pseudopotentials is a pre-requisite for any successful calculation. You should always test pseudopotentials on simple systems before trusting them!

Those that fit your needs in terms of transferability and computational efficiency, for the calculations you want to perform. Choosing good pseudopotentials is an important part of an electronic-structure calculation. Are you sure you really like somebody else do this for you? Please have a look at the various links and resources of the pseudopotential page.