Hmmm... I think Gajim supports Carbons and maybe some other 'modern' XEPs. Stable Psi is quite outdated, but its cousin Psi+ might support some of that, since it has so many extra things.

Swift is a pretty modern-oriented XMPP client, but I'm unsure about its XEP support for such things. I know it supports Delivery Receipts, which, used with a phone-using contact should be cool =)

Then there's the TKabber beast, which is not "modern", but has always supported lots of stuff, so who knows...