In this work, a fast, generic system-level design and optimization methodology is presented for futuristic devices. This work evaluates GaN Heterojunction TFET, WTe2 Two-dimensional heterojunction interlayer TFET (ThinTFET), and WTe2 Transition Metal Dichalcogenide TFET (TMD TFET) in terms of performance and energy-delay product (EDP). This study investigates the impact of device-level performance on the system-level performance and power dissipation. The system-level methodology uses a generic model that utilizes a stochastic wire distribution to estimate system performance. An optimum supply voltage and gate count to achieve maximum throughput is examined for each of the devices using an empirical CPI model under different power budget constraints. Based on this study, the optimal design of each beyond-CMOS device technology is demonstrated to improve EDP. Results in this work delineate an optimal EDP for a given range of power budgets, and provides insightful trends on key design parameters as well as optimal performance and power metrics based on the fast system-level optimization at the early design stage.