The obvious answer would be my Dragon Boxes, but they're some of the easier ones to find and I haven't really had them all that long. Same goes for my Limited Edition copy of Battle of Gods- it's not rare yet and it's still new. Once I get the poster and the postcards framed, I'm sure they'll be right up there in a couple of years. I also enjoy having the two art-books that I own, and I feel like my collection would be missing something if I didn't have my Manga volumes there.
I think I'm gonna have to be different here and say it's the Remastered Double Features.
I know it's the "faux-remastered" stuff, but I do have a lot of nostalgia for the movies and I think these DVDs really capture my a certain aspect of my fandom. It was the first release that I actually kept up with and something that I bought, pretty much, as they were coming out. The time-frame in which they were released is also when my interest in the franchise really took to a new level and I really find it fascinating how I ended up going through all three audio tracks in terms of viewing preferences. I started out watching the ENG dub w/ the US score, before moving on to the ENG dub w/ the JPN score, and finally I arrived at the "Original JPN Audio Track"- and I've stayed there ever since, apart from a few exceptions (cough, DBZ Movie 5). 
Fuck, can I just say all of it?
