I'm certainly not a power user. I mainly use Twitter to keep up with friends and acquaintances in the tech community. None of the other platforms seem appropriate for that.
Tumblr is another blog/social hybrid, but in your particular case you're subject to network effect (or the lack thereof) in your community of interest. Also, Tumblr is similarly faltering in engagement and owned by a corporate parent that is trying to leverage it as part of a wider strategy to turn its fortunes around.
