I can also recommend a console client (in Haskell) - Matterhorn [1]. For me, the biggest obstacle right now is the lack of support of chat categories in mobile [2] client and Matterhorn [3]. These chat categories are available in the web interface.

[1] https://github.com/matterhorn-chat/matterhorn

[2] https://github.com/mattermost/mattermost-mobile/issues/5387

[3] https://github.com/matterhorn-chat/matterhorn/issues/711