I just cranked my reel up (a Technics RS-1500), and right off the bat Lee Morgan's trumpet was in the listening room; I didn't have to make any effort to know that the reel was better than anything else I have, it just is.
If I didn't own a reel, I wouldn't buy one; there are a lot of things you have to know when you own a reel. Although I have learned those things, I still have to go over the check list in my mind when I get involved with the R to R. Magnetism is so taboo, and you have to demagnetize the heads. When you do this, you have to remember to move all your recorded tapes a good distance away, or you will mess them up; over the years I've accumulated quite a few, so that's a headache.
Bigger is better. When you compare the size of a cassette tape head, to the size of a R to R tape head. Stereo half track sounds better than stereo quarter track, assuming that both tape decks are of the same quality.
https://www.google.com/search?biw=1024&bih=662&tbm=isch&sa=1&ei=caUcWrqIBKrVjwSFgIiw...:
When you compare the convenience of all the digital methods of record and playback, one has to be an extreme audiophile to opt for reel, but for those who must have the very best, there it is.