The concept of urban air mobility promises a modern air taxi transport solution providing on-demand air mobility and hence time savings compared to congested terrestrial transportation in major cities and metropolitan areas. To make it a reality, vehicles, infrastructure, services, and operations must be developed simultaneously and cross-linked. These interconnections and interactions of the multitude of systems involved necessitate a system of systems approach, which is accounted for and implemented through agent-based simulations. Accordingly, the system of systems simulation framework is tuned to vehicle architecture as well as fleet design and assessment, thus allows to expand the aircraft design process by fleet operations and transport network perspectives. In this paper, the top level aircraft requirements of electric vertical take-off and landing vehicles are investigated by a fleet-centric approach. Herein, two disparate configurations, i.e. multirotor and tiltrotor, are modelled to depict representative wingless and winged configurations. The optimal design points are found and traded off by formulating different measures of effectiveness accounting for conversion of passenger requests, fleet energy consumption, and vehicle load factor. In summary, this study demonstrates the need for system of systems simulations to derive market-and operations-tailored vehicles and fleets. Furthermore, work on heterogeneous fleet compositions is required.