Number one: Ain't nothin' perfekt! Storage is a matter of what is to be stored, how long it is to be stored, and how it is to be stored. And don't forget: How ya gonna decode it, play it back, at the end of time?

While I believe that magnetic media have gotten a bad rap against digital storage, I have had some non-perfect experiences with reel to reel, specifically musical recordings purchased on the market in the 60s.
I believe that reel to reel tapes are not as bad as some folks have implied, but are NOT the permanent answer. Check out references to "Sticky Shed" phenomenon.
My family had a repository of reel-to-reels. Analog music.
I found some recordings of Gilbert & Sullivan were a bit degraded and were exhibiting sticky shed. I was able to play them for digital conversion by 'baking' the tapes first according to instructions I found on the web.
I found the DECCA label popular music to be in excellent shape.
Likewise with cassettes. Some pretty cheap makes of cassettes have both mechanical and tape quality issues. Others, like Maxell, and TDK brands, have held up well.
And CDs can degrade on the shelf because that's an awful thin layer of metal with millions of holes in it, and the metal can oxidize. I don't know for sure about DVDs but I suspect they have the same issues.
Sound has only been preservable for about a hundred years, Hi-fi sound only since the mid 50s. Digital hi-fi since the mid 80s.

Remember it's not only the reel to reel tapes you've gotta preserve, it's the reel to reel tape player!