We recommend CC BY and CC BY-NC. 

These licenses allow other scholars to build upon authors' work by creating translations or other adaptations, and do not dictate what license – if any – those new works must carry. If a journal wishes to qualify for the newly developed DOAJ Seal of Approval, it should implement a CC BY, CC BY-NC, or CC BY-SA license, according to the new DOAJ Application form. We anticipate that many journals will find it desirable to obtain a DOAJ Seal. OASPA (the Open Access Scholarly Publishers Association) strongly recommends CC BY as a best practice.