Rural areas of sub-Saharan Africa experience little progress towards universal access to clean cooking, resulting in environmental, socio-economic, and health burdens from the continued use of traditional cooking practices. Energy-efficient biomass cookstoves (EEBCs) are promoted as transition technologies to alleviate these issues, but different EEBC models vary widely contributing to a poor understanding of the relative costs and benefits of the various stove technology options. We examine the impacts of two types of EEBCs, comparing low-cost locally produced stoves designed to achieve fuel savings with more expensive imported stoves expected to have additional health effects. The study is based on a randomized controlled trial among 525 households in rural Senegal. We find the two EEBCs to perform similarly in terms of reducing fuel consumption and diversifying household fuel use, with no significant impacts on cooking and fuel collection time, or emissions. Consistent with the muted impact on emissions, no objective health improvements were detectable for either of the two stoves in this real-world study. We conclude that the cost-effectiveness of the technically more advanced option appears to be low, while the low-cost EEBC can be seen as a bridging technology that seizes external environmental effects, but in the medium term, fully clean technologies will be needed to realize a wider range of benefits.