Quality wise, I am surprised so few friends/members here have R2R.
My Reel to Reel is the best sounding source I have. Same content/different formats: Everyone here picks tubes over solid state; lps over cd's; r2r tape over lp.
In my case, I have two of Teac's last Prosumer 4 track 6 head auto-reverse model x2000r. same as x1000r except 2000 has colbalt heads, Big and small reels, but 7-1/2" speed. It isn't as good as 15 ips, or 2 track, but it still beats anything else I have. Tape hiss, yes, and yet it's better! I've made two nephews involved with music industry cry while listening to Sgt. Pepper's.
My friend has two Otari's, 2 track, 15 ips. Incredible, he played Led Zeppelin's 1st album among others. Holy smokes, now you know what they were hearing in the studio, so much more listenable than 7-1/2" 4 track. He pays a lot of money from certain sources for tapes, primarily Jazz (some sources are not great). Most sound amazing, a few, not outstanding
I had early 2 track stereo tapes, 7-1/2 ips, definitely sounded better than my 4 track.
A problem is that pre-recorded content is age related, and simply stopped being made/released. The early 2 tracks are mostly classical. The 4 tracks have all the wonderful 50's, 60's; 70's, I think into earlt 80's.
If you are younger, none of your favorite artists exist pre-recorded R2R.