Is it better to hire a digital marketing professional and have him/her in-house, or avail of digital
If your business can afford at least 1 content writer, 1 visualizer, 1 graphic designer, 1 video editor, 1 social media manager and above all an HR manager then you can have in-house digital marketing team.
Ideally for small and medium business enterprises it is not feasible to have such a large team. Some may argue to have one person with multiple roles but that will not justify each role to the 100%.
Having a professional agency to work for you will bring the latest tools and techniques of digital marketing for your requirements. The agency handling multiple clients will have better know how on handling the various challenges coming up during any digital marketing campaign.