Qutecom is a very fine VoIP client running on Windows/Mac/Linux already. It’s the official successor of Wengophone. Has anyone gotten around to trying to port it already? Unfortunately, I don’t know enough of C++ to do it myself. :/
There are few Jabber clients who support Jingle (real Jingle, not only GTalk), let alone encryption via SRTP. :/
What features do you need?
I need: chat, file transfer.... voice is a pluss, channel encryption is a pluss
that's all I ever need
It's more about how rather than what. Presence, IM, voice, and video are possible with both protocols, but each has a different slant on how those functions work which makes neither protocol ideal for all environments.