We use Wire. In some respects it's more useful than Signal, because it works on mobile, desktop and web. I think the desktop clients are Electron based, so I use the mobile and the web apps. You don't necessarily need a phone number, it can also use an e-mail address, so it works just fine on the desktop. It also has voice chat and conference. Oh and a good part of it is open source, although it's uses a centralized server.
I second the Wire recommendation because you can sign up with an email address, and conversations sync across devices. Its feature set is also good (not as good as Telegram) and improving. I wouldn’t recommend Signal as it is still poor in features, speed and stability.
With Signal you cannot carry your chats to a new device (this is prohibited by design in the app on iOS)!
If you want to experiment, try both Wire and Signal at the same time, and you’d observe the differences quickly.
