I have both disks. AVIA is more user friendly compared to DVE, easier
to navigate through the tests. However, DVE can test for BTB (Blacker
than Black) which AVIA lacks. I think both were designed initially for
the older type of TV (not DLP, LCD or PLASMA) however, some of the
major test you would be able to use if you have one of those types of
TVs I mentioned as well.
If you have a THX DVD (i.e. star wars), it has a THX optimizer that you
can use initially to tweak your video settings until you get either one
of the disks. If I'll make a choice all over again, I'll get DVE
because of the BTB tester (I got AVIA before DVE).
Here's some more info for you.