Hard drive, at least you know you're the only one watching. Make multiple copies if you fear data loss, or store on cloud only after putting them in a password protected (encrypted) .rar/.7z file (with a password that isn't your name or anything trivial, possibly, lol)
Y'know how streaming movie websites rotate their media, and how some movies or shows seem to disappear? I feel that that might happen to my data. A 4 TB hard drive is about $100. I would go that route. Need a backup? When you can afford to do it, buy a second one and keep it in a safe deposit box or something like that.