Paper. It's arguably the only medium that's survived through centuries and remains virtually unchanged today. TV and radio have gone either HD and/or into space (via satellite) in less than a century, VHS enjoyed barely 20 years before being usurped by DVD, 8-track was practically stillborn, Laserdisc is gone completely, vinyl is only appreciated as a novelty now, e-Book readers pre-Kindle and Sony have disappeared, Minidisc was crushed by the iPod, 8mm home movies were replaced by tape then by digital all in the span of about 30 years, only the DS supports cartridges now, CD-Rs are cheaper than floppies, and when was the last time you had to buy a tape for an answering machine?
But paper (namely books) are the same now as they were at least 1000 years ago. That's pretty impressive.