There exist many clients supporting the XMPP protocol. Personally I have tried the following:
I recomend to use Gajim on your computer and Conversations on your phone because they support Carbons, MAM and other nice to have XEPs which will make using XMPP very pleasant. Actually it can totally replace your other instant messaging services like that. When using Gajim I recommend to go to Edit -> Plugins and enable the following ones:
- OMEMO Multi-End Message and Object Encryption
- Url image preview
Zash created a very good, though not complete, site listing clients and the XEPs they support. I recommend that when choosing a client and having some technical background you check his project Similarly he offers the the same for server software which shouldn’t convern you unless you decide to setup your own server.
Note: if you use a client that is not listed there you can add it and send a pull request to Zashs git repo.