This paper aims to develop a shortlist of the most relevant criteria for the selection of transportation service providers in Vietnam. Opinions from local experts are gathered and analyzed using the Content Validity Ratio method. Specifically, their qualitative judgments are converted into quantitative data, with which the most essential factors can be identified. The results highlight that in the context of choosing a partner for transportation service, cost, client relationships, responsiveness, service quality, ease of communication, awareness of ethics, awareness of health and safety, delivery performance, and information sharing are top priorities for decision makers, while environmental factors, such as the adoption of green technologies, are less critical.