Across the world, the biggest smartphone manufacturers are Apple (28%), Samsung (24%), Xiaomi (12%), Oppo (6%) and Vivo (5%). However, there are geographic patterns in popularity, with Apple dominating North America and East Asia, while Samsung leads in South America, Europe, Africa and West Asia in addition to its home turf of South Korea. Xiaomi is the most popular phone brand across South Asia, Spain, Venezuela, Ukraine, Madagascar, Kyrgyzstan and Palestine, while Tecno is popular in West and Central Africa. Oppo, Vivo and Huawei lead in Indonesia, Bhutan and Togo respectively.
RCS is a pile of garbage for many reasons. On Android, it’s locked behind Google’s proprietary, privacy-invasive Messages app, and there is no API for third-party RCS clients (like with SMS). The encryption is also implemented in that proprietary client, offering no transparency and meaning that it’s probably backdoored. No one should ever trust encryption software if its source code isn’t public. People should use actual private messengers like Signal, with open source applications available for all platforms, as well as all of the features you mentioned. The only thing it obviously lacks is SMS fallback, but it’s really unnecessary, because Wi-Fi or cell data are literally available everywhere nowadays.