What is the best Reel To Reel machine ever built?


Everyone who has listened to master tapes or dubs knows about the well balanced sound they provide. But it is also important to have a fine tape recorder or playing machine to enjoy the tapes' qualities in a good system.
Maybe my question was raised once before but the relevance of the topic is now greater as the tapes are back to more and more audiophile friends, especially those who are owning excellent phono chains.

I have seen many big & professional machines being recently offered and sold on e-bay, Audiogon and other platforms and I am discussing within a small group which machine is really the "holy grail" among the R2Rs. So why not here. I am interested in findings.
thuchan
the ATR is a Mastering Machine.
I read: The Ampex ATR-102 tends to work best on rock, metal and hip hop styles, and even folk or acoustic-based music that needs ‘warming up’. Where it doesn’t work well is when a mix is already quite compressed, dull or heavy in the low frequencies – in these cases the tape only tends to exaggerate these areas.

best & fun only
Thuchan, please elaborate on how the R2R application is coming back. What is the source material and where can you buy it?? I have zero knowledge about R2R, so a brief education would be appreciated.

FWIW, I remember in the "old" days when high end R2R machines were made by Crown, TEAC and Tandberg. I never got into that end of the hobby but these machines were works of art, especially the Crown which was the Cadillac of the day.