I have thousands of photos I've taken over the past few years. I back them up to archive quality DVD such as these.
Gold DVD. I write the DVD and store it in a jewel case in cardboard boxes under my desk at home. I don't consider any form of a hard drive to be reliable long term storage since the hard drive itself is a relatively fragile piece of electro-mechanical equipment that is sensitive to being dropped, misplugged, etc. Also, I'm not so sure about the long time reliability of the mechanical or electronic components. Electrolytic capacitors, for instance, used to leak and corrode. Maybe that's changed.
CDROM and DVD, if properly cared for and quality media are, as far as I am concerned, more reliable media.
As far as technology shifts, I bought my first PC in 1992, which had IDE drives. More recent drives are either SATA or USB, with IDE being less popular. I got my first CDROM drive around 1994, and CDROMs had been around for a few years before that. Current DVD drives can still read CDROMS, so I think the risk of technology change rendering DVDs (and CDROMs) useless is small. There's going to be a lot of angry people if CDs and DVDs are dead in the next 5-10 years.
A couple notes.
I realize I should be keeping my media somewhere else than home, but I don't have alternate storage space.
Also, do not rely on commodity grade CDROM or maybe DVD for long lifetimes. I have a fairly large number of audio CDs that I burned 10-12 years ago that have been gradually failing over the last 3-4 years. Some are still good. I thought I got a deal one time on some cheap commodity media. That started going bad within a year.