Aside from Eric Roberts, I have no idea who has art anymore.
Brian certainly has the most stuff in terms of rarities, boxes, etc. I'm much more limited as I'm only interested in the stickers, packs, wrappers and boxes.
Bill F. (Kook) has a lot of cool stuff, and there are a couple of registry set collectors who have incredible graded sets. They are rarely if ever on here. I'm sure there are others who have stuff to differing degrees. The vintage collecting community is nowhere near as close knit as it used to be unfortunately.