I personally think most of things would work better as not box sets. Box set seems most valid in case where releasing multiple identical releases makes hardly sense, but extended to box set works out. Live stuff, tapes that hardly qualify as "albums" etc.
but if we talk about theoretical releases:
*Con-Dom "sermons" would be essential. But that's a double cd at max, not a box set? Thematically, I don't think anything else should be as filler. Perhaps the original 25 copies special version, the altar with 8 x 7" and booklet etc sums up pretty much what it would be to be complete?
*Some of Grey Wolves tapes would most certainly stand out as single albums, but in other hand box of old tape on CD format probably better than to release as if they were intended to be "real albums". I would hope their real albums would be released separately as proper CD's. Not as box-set.
*Deadline Noise Productions 90's rarities box. I think among ridiculously limited tapes there are golden stuff. RR, BLJ, related.
*Taint box - if tapes don't feel they stand alone as proper "albums", archive box of CD's would solve the case!
*Monde Bruits -complete box
*Aube -the early days on real CD, not as CDR like it was done