Regarding Wickr:
isec partners spent 9 person-weeks
https://www.wickr.com/about-us/blog/2014/08/08/isec-partner-...this one spent 240 hrs: https://www.wickr.com/about-us/blog/2014/08/05/aspect-securi...
You haven't talked about Wire.
People have to trust someone. If you are not a crypto expert you have to rely on crypto experts to tell you if the protocol/app is sound.
I don't have to be a security expert to know that google can get the phone numbers of all the contacts I talk to on Signal. So the anonymity angle is lost completely.
Regarding privacy, I don't have to be a crypto expert to know that google services are running as root on my phone. They can easily replace the app itself. Avoiding using google proprietary services and still using Signal is a lot of pain.