I've only used DVE, my sound system is not yet complete, so primarily my purchase was based on the video portion. I have read that the video part of DVE is better than Avia, but I have also read that the audio portion of Avia is a little better than DVE. Also, the general consensus is that DVE is more difficult to navigate.
I think many people here, and on AVS, have tried and/or own both.
Good Luck!