Thermal energy storage is emerging as a sustainable and innovative solution for industrial heat decarbonization. Packed bed systems offer low costs, high energy density, and efficiency for medium- and high-temperature applications. This study evaluates the performance of various packed bed configurations using commercial ternary salts and silicone oil as heat transfer fluids, benchmarked against solar salt. Copper slags, steel slags, and bauxite are selected as suitable solid media, and the combined effects of the material properties in each system's technical performance are analyzed using computational fluid dynamics simulations. A numerical model is developed in COMSOL Multiphysics, using an axial-flow packed bed system as the base design, and all configurations are simulated. Key performance indicators such as round-trip efficiency, thermocline thickness and material cost evaluate the findings. The study reveals that ternary salt packed beds exhibit significant flow non-uniformities under specific conditions, driven by ‘viscous fingering’, leading to round-trip efficiencies below 80 %. Silicone oil achieves low thermocline thickness, round-trip efficiencies near 90 %, and costs of ∼€12/kWh with metal slag fillers. Steel slags consistently yield higher efficiencies, while copper slag offers greater energy density, reducing storage costs compared to bauxite. Sensitivity analyses are performed for the ternary salt systems in order to identify the boundaries of ‘viscous fingering’ and are benchmarked against solar salt. In comparison, solar salt demonstrates the lowest material costs (∼€3/kWh) and round-trip efficiencies near 90 %. This work provides relevant insights for detailed thermocline TES design when considering non-conventional materials, enabling reducing costs whilst ensuring relevant efficiencies.