All of mine. Music, photos, copies of important documents, archived sets of email (and gmail) across different eras. My facebook archive export, IRC & IM logs stretching back to ~2000. A lot of it even on SSD, let alone HDD's, let alone "archival media". The spinning rust is mostly used for double- and triple-redundant copies of my music and photos, as well as the usual movie collection.

I'm not sure HN is the best place for such... technological anachronistic skepticism? A lot of us ARE going to be storing all that for shits and giggles.