A lot of us know the features of each but I cannot think of a site that compares them. I used to have Video Essentials then I got AVIA when that came out because of its expanded video test signals (and audio too). I recently sold that off to get DVE because of the 6.1 among other things. It was also quite cheap compared to AVIA.
Well for those interested I found a way to compare calibration discs. Hope this is of some use to those considering which one to purchase. http://www.videoessentials.com/ve_d_high.htm