I have been working on both formats for a long time now, and I hope my feedback will be beneficial for you.
Advantages of Job Portals:
• Easy to access.
• Good for mass recruiting.
• Large number of options for candidates.
• Economical.
Disadvantages of Job Portals:
• A specialized person is needed to do shortlisting from a large number of resumes.
• Many candidates apply just for the sake of applying; very few are genuinely interested.
• Even after lining up candidates for an interview, there is no assurance they will come for the interview, and proper follow-up has to be done.
• It is time-consuming.
• Strictly not a good option for filling senior/confidential positions.
Advantages of Recruitment Agencies:
• They have good contacts with candidates, so it is easy to contact suitable candidates.
• Good for senior position headhunting.
• Candidates generally turn up after being lined up for an interview.
• Only those candidates apply who are genuinely interested.
• Easy to do reference checks.
• Even if a candidate leaves after joining, we have a replacement.
Disadvantages of Recruiting Agencies:
• There are lots of agencies in the market, so pointing out good agencies is a big task.
• Generally, agencies specialize in a particular branch of recruitment.
• It is a bit costly.
Regards