It’s easier than ever to get your own SIPs account, whether you’re making it through Ekiga, a third-party site or even setting it up yourself on a home server. Jitsi is the app that gets the very most out of whatever you set up, even if you don’t plan to use SIPs. Thanks to its ability to connect to other chat services, it becomes an all-in-one chat and IM client for however you want to contact people.
The sheer wealth of settings available in Jitsi is also astonishing, allowing you to tweak specific timeout, port and other connection settings you may never actually need to change. The rest of the clients did not offer settings nearly this deep, and the codecs available were definitely a plus.