A large number of alternative fuel molecules based on lignocellulosic biomass have been proposed recently, but a reliable evaluation of their economic potential is challenging due to the limited data available. A rapid screening methodology, Reaction Network Flux Analysis (RNFA), has been suggested to screen a large number of future reaction pathways. The RNFA is extended in this work by a comprehensive sensitivity analysis to account for inevitable uncertainty in the underlying data and hence in the ranking of biofuel candidates with respect to cost and environmental impact. The extended RNFA is then used to assess and rank candidate reaction pathways and associated processes for the production of a variety of proposed future pure-component biofuels from lignocellulosic biomass. Ethyllevulinate and 2-methyltetrahydrofuran have been identified as promising alternatives to bioethanol, while lignin-based biofuels can be excluded from further consideration. Methane is found to be attractive economically but shows significant environmental impact.