For E2E? there's essentially PGP (sucks, see thread from the other day. worst user experience and questionable longterm security), OTR (most used, still annoying to have to re-establish sessions on restart, no multi-device), and OMEMO (based on signal, should be the future for XMPP). You could include most proprietary solutions like iMessage that usually miss authentication or are done unsafely.
OTR not trusting fingerprint is the default case for any authenticated standard. gnupg requires that you set the trust on a key. Signal allows it initially, warns if it changes.
For all the above though, they aren't a packaged solution that is user friendly. Conversations is a great android client, but there's sadly nothing comparable on iOS (chatsecure, but it's alpha status still). The desktop situation is hit and miss too (I was a pidgin user and moved to bitlbee for OTR, still don't have an omemo solution... though my setup doesn't need it through a TLS secured ZNC).
OTR not trusting fingerprint is the default case for any authenticated standard. gnupg requires that you set the trust on a key. Signal allows it initially, warns if it changes.
For all the above though, they aren't a packaged solution that is user friendly. Conversations is a great android client, but there's sadly nothing comparable on iOS (chatsecure, but it's alpha status still). The desktop situation is hit and miss too (I was a pidgin user and moved to bitlbee for OTR, still don't have an omemo solution... though my setup doesn't need it through a TLS secured ZNC).