Unfortunately, there's no right answer, but there are times when one is more effective than the other. Your resume is effective only if it leads to interviews. You have approximately 15 seconds to engage a prospective employer and convince him that your background warrants attention. Your document must speak loudly and clearly of your potential value and compel the employer to call. Comprehension greatly improves if you provide only the necessary information on one sheet of paper.
Time equals money Most hiring managers are short-staffed and busy.
Many say a one-page resume is likely to get their attention. Some won't even look at the second page, unless the first page has caught their interest. Resumes were never intended to include everything candidates accomplished in their careers. The second page of a resume typically involves first jobs, educational credentials, personal data and military service. Much of this information is ancient history or shouldn't be included.