Client-vendor relationship has been considered as a critical and even most critical among other ITO key success factors. for a successful relationship, the client should firstly clarify its expectations as a foundation to assess and select the best vendor proposition to fulfill the expectations. for that reason, this paper is focused to propose criterions to evaluate the best vendor's propositions and capabilities to fulfill the benefits. with a clear understanding on each of the criterions, it is hoped that a client organization could have better and richer information to properly consider which vendor to be engaged.