I disagree about rejecting funding from intelligence agencies. I hate the concept of their existence, as well as what orgs like the CIA have done (and proceed to do) but given the fact of their existence, they do have legitimate reasons (in this case I mean reasons that align with Signal’s current goals rather than in order to change them) to fund Signal, and if that results in funding secure software, all the better.
It definitely has its roots in Debian, but when you need to use that weird closed source application for work, if it has a “supported” (for a given value of support) Linux distro it’ll be Ubuntu.
I personally prefer straight Debian myself, or something entirely different but when asked for a recommendation by friends it’s Ubuntu.