Signal sounds nice but it's a bit overbearing - backups are somewhere between difficult to impossible depending on the device, there is no web client, and it's only open source in that you can audit source or run your own independent chat network (3rd party clients on the official server are treated as hostile) not as in it's an open community. Despite all of this kind of stuff being defended for contrived hyper-secure hyper-private reasoning you can't send a chat without giving out your phone number and it's ridiculously easy to cause your verification number to change making people numb to all of the protection in the first place.
I did grab a Telegram account recently but only since Beeper supported it and I figured "why not" so I'm missing out on these features but I almost wonder if I would have even been so excited about new things like Beeper had I went Telegram originally.
Interestingly of all the chat apps WhatsApp and Telegram usage seemed to align heavily. Not sure if that was just a quirk of my friend group or a more general thing.