Neither is automatically better in every situation. A bank generally offers its own products and pricing. A mortgage broker can compare options from multiple wholesale investors, which may create more flexibility for pricing, property types, credit profiles, and complex income.
The person handling the loan still matters. Compare responsiveness, experience, transparency, loan choices, total cost, and the ability to anticipate problems. The right question is not only where the loan comes from, but whether the advisor can explain and execute the plan.