Jabber and XMPP aren't really alternatives as they are just protocols. They don't have a stable feature set and aren't necessarily encrypted by default.
Many Jabber clients do end-to-end encryption by default. I would not care too much in the age of #surveillance directly at the source, i.e. on the device 🤷
If you want an even more coherent feature set and also be sure, all your clients encrypt by default, your best bet is #Snikket by @snikket_im. Highly recommended!