Low Power Wide Area Networks (LPWAN) have emerged as an appealing IoT communication solution. Large coverage and low power consumption are critical requirements when deploying a communication network to support an IoT application. Despite the fact that existing LPWAN technology solutions promote IoT requirements such as long communication range, energy efficiency, scalability, and low cost, there are numerous concerns about the performance of this type of communication network. With a wide range of LPWAN technologies available, there is growing interest in their evaluation. This paper proposes an experimental comparative evaluation based on coverage and energy-efficiency test performance for LoRaWAN and SigFox, two emerging LPWAN technologies operating in sub-GHz Industrial, Scientific, and Medical (ISM) frequency bands. Recent works have presented various comparison studies of LPWAN technologies, however most of them have been tackled from the perspective of comparing their technical specifications without presenting measurement results obtained from network deployment scenarios. We argue that by proposing a comparative evaluation from an experimental perspective, the comparison discussion is taken to the next level. The experimental evaluation has been proposed first by selecting coverage and energy-efficiency as the most significant design goals for LPWAN applications. Second, by proposing the test performance to evaluate those goals, where extensive measurements are made in network deployments, and finally, by highlighting the main findings about performance for both network for comparison purposes. Results show that in a test with fair conditions LoRaWAN performed better than SigFox in an urban environment in terms of coverage, obtaining a better packet delivery rate (PDR ≳ 80%) with higher radio strength signal (RSSI ≳ - 110 dBm). Whereas Sigfox shows better energy efficiency with a 20 % of more sent messages under the same test conditions.