Wire

I'm the Principal Investigator of an NIH funded research study using Wire to deliver group therapy via text and video-calls to people with a serious mental illness. So far, participants and staff have greatly enjoyed the interface, its innovative features, and the user experience in general. In particular, the group video-conferencing feature allows for smooth and high-quality group calls from mobile devices. In summary, the software has exceeded our expectations in terms of reliability and functionality.

If I were to pick one area that could be improved, it would probably be the option to easily download and securely archive existing text-based group conversations, which isn't currently available. However, it is my understanding that Wire has plans to develop this feature moving forward.

As a chat app very simple to use and setup. UI is basically chat but nothing else. Self-destroy message makes sharing sensitive info easy. Secure voice calls and video calls quality are surprisingly high. Pricing is very competitive compare to other US rivals. Europe-based company.

Wire is basically just a chat software. Integrations with 3rd-party almost non-existent. Syncing between devices have issues sometimes that re-sync with new encryption key may be required. Syncing chat history takes longer time than usual.

for private use, Wire is free of charge.
You can send various files in encrypted form.
This messenger is very secure and encrypted, so you don't necessarily have to enter your number, your email address is enough. This way it remains more anonymous.
The functionality is very good for a free private encrypted messenger and so I find it very good as a price/performance ratio because many don't want to pay and so some come to these messengers.
You can send audios with unlimited duration and you can listen to them very well.
I also like the design but it's a matter of taste.
You can make encrypted group calls, which I like and use.
The quality of the calls is also very good with the loudspeaker function

Limited functionality:
you cannot change the background screen
you cannot send stickers like in whatsapp
if it is an encrypted messenger, then you should not be found by the other contacts in the list, but maybe by an ID. should be better anonymous, instead of finding the names in the list.
You have a limited choice of ring tones to choose from.

Security and Privacy and ease of use. Also, the options to sign up either by phone number or an email.

Unsure of making bots to prevent sharing suspicious links or prohibiting calls to unknown users.