This question doesn't really have one answer for all professions. A college diploma is still very important for jobs that require certain formal education and is an administrative requirement in many companies. College also provides a broader knowledge base, experience working in an academic environment, and opportunities to build networks. But in some fast-growing fields, certifications and practical abilities can be additional proof that someone has certain skills. Therefore, comparing diplomas and certifications as if one of them is always more important is not appropriate in my opinion.
The strongest thing is a combination of education, skills and proof that we can really work. Someone may have a great degree but struggle with practical tasks. On the other hand, someone can have many certifications but have no experience applying their knowledge. Portfolio, real projects, work experience, communication skills, and results achieved often make the difference when candidates enter the further selection stage. So if you have to choose, first look at the field you want to enter. For certain professions, a diploma is a mandatory foundation. For other fields, certification can be a strong added value. The most important thing is not the number of documents you have, but the ability that can actually be proven.
