There is a desktop client though.
XMPP is quite popular right now, but I have to say that none of my contacts use this protocol. As it is easier to change messaging apps than friends, I stopped using it.
I have tried Wire with a friend, but quite briefly. Nice design.
More info on different options in this thread:
About the eternal Signal vs. Telegram discussion, this article is more up-to-date that the one quoted above: Telegram vs Signal: Which is More Secure and Private App - TechWiser
And Telegram’s FAQ is quite interesting about multi-device end-to-end encryption:
Multi-device End-to-end encrypted chats are a mess
The concept of End-to-End Encryption has no limits for the number of communicating devices. However, if you want to access your end-to-end encrypted chats from multiple devices, you’re facing many technical difficulties, especially when it comes to connecting new devices, loading chat history and restoring backups.
Most of our competitors (notably, Whatsapp and iMessage) solve these problems in ways that make their end-to-end encryption useless (this is a big topic, so requires a separate manual). To solve them in a secure way, you’d have to sacrifice usability and some of the features you’re used to – the result would never be as fluent and simple as what we offer in Cloud Chats.