A comparative analysis of three distinct classes of self-sufficient nuclear energy systems is undertaken: 1. fast breeder-converter system 2. deuterium-tritium fusion reactor 3. fusion-fission hybrid/symbiont. Consistent power and isotope balances are imposed and relevant performance criteria are established. While no one system seems to excel in all physical criteria, we find that the improved neutron economy of the combined fusion-fission system provides the basis for a substantial and enhanced range of fuel and energy production capacity.