Personally, I thought both were garbage. Buggy, laggy - not ready for prime time over 3g that's for sure. Hopefully Epic w/ better video processing and framerates may help these apps... one can only hope.
I think the issues are all software related. If you could combine both apps, you'd have a winner.
Fring has pretty good video quality, horrible audio quality. There's an audio feedback loop that is basically unavoidable. And you're limited to the front camera. The video quality is pretty decent though, even though it's limited to the front camera. No bluetooth support though- not even my bluetooth that has A2DP works with Fring.
Qik has absolutely horrible video quality. You can't even really tell what you are looking at unless someone tells you or you already know. You can, however, switch to the back camera- but the quality is still way too crappy to use. The audio is good though. You can use a bluetooth headset if you want (at least mine works, but it has A2DP so that may be required). One party has to push a button to talk, like a walkie talkie, so there is no crappy audio feedback loop.
If you could give Qik Fring's video quality, it would be awesome. And if you could give Fring Qik's ability to use the back camera, Qik's ability to use bluetooth (even if only A2DP), and Qik's audio quality (no horrible audio feedback loop), then it would be a great app.
Either way, I don't think the Epic will solve any of those problems unless the apps themselves get updated.