Well my personal experience is that the best is the "paper"...
but in digital life... you must have many backups...
1) CD-DVDs.... I have many projects 20-25years... in expensive DVDs... that have holes in their magnetic... surface :-( (i think that can live for sure in special cases... about 10 years)
2) HDD's ..... mechanical hard disks... with data... (better change them every 5-7years)
3) SSD.... you never know... may be live - may be not (all about chips and current)
4) USB sticks... need to put them every some months to a usb (charge them, is a flash memory...) - many of mine oxidized :-(
5) CLOUD... google, onedrive... need to pay them a lot... and who knows ... what they are doing with your photos
