One of the most important issues of the fourth generation (4G) wireless networks is the capability of mobile devices of handing off running communication sessions to the appropriate interface. It is widely accepted that the handoff decision must consider users, terminal, and network criteria. In the last ten years, several multi-criteria decision mechanisms have been proposed to solve the handoff decision problem. However, it appears that the criteria's choice is somewhat arbitrary and some of the proposed mechanisms even give arguable results. In order to better understand their applicability, we compare extensively by numerical simulation the performance of multicriteriadecision algorithms for vertical handoff. We evaluate each mechanism by considering specific requirements for different classes of service.