The deciding document is whichever one satisfies the qualification rule written into your specific Appendix 2 entry, because those requirements differ from occupation to occupation. A general degree, a long employment history and a warm reference decide nothing if the entry demands a particular credential you do not hold.
Match the credential to the entry, not to the résumé
Read your entry and note precisely what it accepts. Some occupations require a baccalaureate or licenciatura degree. Others are satisfied by a diploma or certificate from a recognised institution once a specified length of relevant practice sits behind it.
Some, such as Management Consultant, expressly permit an experience-only branch, and a few turn on holding a licence rather than on any degree at all. Hypothetical example: a writer producing installation and service manuals at a Saint-Cyrille-de-Wendover plastics moulder holds a literature degree and an employer letter naming her Documentation Lead; the useful move is to select the Technical Publications Writer entry, satisfy the requirement that entry sets, and have the letter describe the manuals she writes rather than a title. Where credentials were earned outside Canada or the United States, obtain a credential evaluation early, because a missing equivalency assessment is a slow problem to fix at a counter.
Where a licence is required, confirm it is a licence of the jurisdiction the rule points to, and remember a professional order membership in Quebec is not automatically the licence a U.S. state issues.