In various projects a large variety of RFQs has been developed, for different application, with different average current, frequency, and energy range. In this article, a comparison, in a scaled way, will be done, using the build RFQs of IFMIF, ESS, SPES, ANTHEM. In particular, the characteristics of the beam dynamics will be analyzed, such as transmission, longitudinal output emittance, and real performance versus simulation.