I've owned Video Essentials and Avia. I prefer Avia, it has a lot more stuff for the money, and the explanations are very good. While reading on this forum I constantly find new uses for test patterns I didn't even know I had http://www.avsforum.com/ubb/smile.gif.
I think each has its good points so if you buy one,shortly after you will want the other. AVIA is much easier to navigate. The little tutorials on AVIA are wonderful. The fine dot pattern on VE isn't available on AVIA and I find this extremely useful to see if my system is drifting. Many of the VE patterns aren't centered and this can result in an increased rate of hair loss if you don't know that(the overscan screen as an example!)