Depends on your archival needs. Consensus seems to be that tapes have a longer unpowered shelf life. In terms of speed it really is cold storage though. You can't just bring the tape over to a user's system and copy a file. And seek times for retrieval of arbitrary files are very slow compared to HDD.

If you really need it to last and re-writability isn't an issue, M Disc claims 1,000 years.