Open Government Data (OGD) initiatives aim to enhance public participation and collaboration by making government data accessible to diverse stakeholders, fostering social, environmental, and economic benefits through public value generation. However, challenges such as declining popularity, lack of OGD portal usability, and private interests overshadowing public accessibility persist. This study proposes an integrated usability framework for evaluating OGD portals, focusing on inclusivity, user collaboration, and data exploration. Employing Design Science Research (DSR), the framework is developed and applied to 33 OGD portals from the European Union (EU) and Gulf Cooperation Council (GCC) countries. The quantitative analysis is complemented by qualitative analysis and clustering, enabling assessment of portal performance, identification of best practices, and common weaknesses. This results in 19 high-level recommendations for improving the open data ecosystem. Key findings highlight the competitive nature of EU portals and the innovative features of GCC portals, emphasizing the need for multilingual support, better communication mechanisms, and improved dataset usability. The study stresses trends towards exposing data quality indicators and incorporating advanced functionalities such as AI systems. This framework serves as a baseline for OGD portal requirements elicitation, offering practical implications for developing sustainable, collaborative, and robust OGD portals, ultimately contributing to a more transparent and equitable world.