I keep all my digital photos on an ever increasing (both in size and number) array of external hard drives. The latest addition is a 3TB (95€ including VAT). So far I've used everything from floppies, tape drives, Zip Disks, CD-ROMs, DVDs, MO Discs...
I'm going through my archives at the moment - a family friend died recently and I thought I'd give her family a collection of all the pics I took of her over the last 35 years or so.
Absolutely no problems with anything on negatives.
(Also, really easy finding a specific picture. Just browse the contact prints, there.)
Some of the slides have started to fade a bit so I guess I'll start scanning them soon.
No problems with CD-ROMs by Kodak. There was a transition phase when I had the negatives developed and scanned in the lab, but not printed.
The CDs and DVDs I've burned myself vary. Yes, top-quality media burned at the slowest speed possible and veryfied (and redundant copies), stored properly. Still some of them show problems already after 5 to 10 years. Thankfully not a problem as I've never had a HDD with pictures on it crash yet. So for the time being I'll keep using redundant HDDs. I'm a bit sceptical regarding SSDs. There is a limited number of write/read operations before they 'wear out', so loss of data is more than just a theroretical possibility. Also, they are relatively new as a consumer product. I'd like to see some long-term data on reliability. Right now I'd rate them as reliable as a DAT tape, but that's just off the top of my head without any research or data to back it up.
Where are the holographic storage systems we've been promised???
Every once in a while you read something about a system in the prototype/proof of concept stage, and then - nothing.
Oh, right, that will host the AI autopilot on my jetpack.