As firmdragon said, stay away from the Hi8, you don't want analog. Between the DVC and the Digital 8 (D8) it depends on 2 factors... 1) size. The D8's are typically bigger than the DVCs. And 2) what formats the stuff you allready have are in. I bought a D8 because all my families old home videos are in Hi8 and the D8 will play those back and do a A/D conversion on the fly. Made it useful for me, but I allready have 2 DVC's so I've got both formats.
Hope that helps a bit
cal