The better option depends on the problem, not the label. A strong independent consultant can outperform an agency for focused work, while a multi-discipline programme may need broader capacity.
A defined audit, advisory need or narrow specialist problem can benefit from direct access to one experienced practitioner. Confirm their available capacity, coverage when unavailable and whether implementation sits with your team.
Technical, content, digital PR and measurement work running together may require several skills and dependable coverage. Ask who will actually do each part, because a large logo does not guarantee senior delivery.
Review the diagnosis, proposed ownership, implementation support, reporting method, conflicts and exit terms. The right partner should be able to explain what they will not do as clearly as what they will.