Just recently there was a HN post about security bugs in Signal. Signal is open source and the bugs will be fixed at some point, but I wouldn't trust all these proprietary apps will follow the lead so fast.
"We've released an update to the Android app (3.19.0) which includes a fix. Signal for iOS and Desktop were not affected, nor were other consumers of Signal Protocol. Non-attachment message confidentiality and integrity was not affected. We're publishing our analysis to make as much information available as possible, but given both the limited impact of this bug and the set of circumstances necessary to exploit it, we consider this to have been of low risk to Signal for Android users."