With the large integration of converter-interfaced generation (CIG) and widespread of power electronic interfaced technologies, power system dynamic behaviour is becoming progressively faster. As a consequence, is often unclear when to use EMT or Phasor models in grid integration studies. Therefore, this paper presents useful simulation guidelines of Voltage-Source Converters (VSCs) used in AC grid integration studies. It also presents several EMT and Phasor models suited to simulate CIG and renewable energy resources connected to power systems. Several modelling approaches and suitability analyses were provided based on a comprehensive comparative study among the models. Various studies were performed in a small system, composed of two generators, and a CIGRE benchmark system, both modelled in Simulink. We address a gap related to the suitability of CIGs phasor models in studies where the boundary between electromagnetic and electromechanical transients overlap. An insightful analysis of the adequate simulation time step for each model and study is also provided.