Global integrators suit multi-year, multi-region programmes with board sponsorship, large application portfolios, and a requirement for one accountable vendor. Specialist engineering firms suit organisations that want senior practitioners working directly on their delivery system, with faster decisions and lower programme overhead. Regulated mid-market companies often fare better with a specialist, where domain-specific governance comes built in. A hybrid model also works: a specialist designs and proves the delivery model, an integrator scales it.