Opinion on Nakamichi azimuth tape decks please

I am thinking of buying a Nakamichi tape deck with the azimuth head adjustment. It will be used mostly for playing of old tapes (that's why I need azimuth). Nak made few of those: 670ZX, 680, 680ZX, 681ZX, 682ZX, Cassette Deck 1, CR-7A, DR-1, ZX-7, ZX-9 and the Dragon. I would not like to spend a lot of money so the Dragon, CR-7A, and ZX-7/9 are excluded. Any opinion on the others? I assume all of them have excellent sound quality; is it true?

I have read that the 680 models have very reliable transport mechanism and other components, but they were made almost 30 years ago. Anyone have recent experience with them? The Cassette Deck 1 was made in 1990-92 (don’t know about DR-1); how reliable are they? Do all of the old Naks require frequent calibration and servicing, and how expensive is it?

Any opinions will be greatly appreciated.
IMHO the Dragon is by far your best bet for playing tapes that were pre-recorded or recorded by other machines. If you get a chance to listen to one you will be shocked at how good even a pre-recorded tape can sound. Yes, more money than some of the others but still less than what most people spend on a pre-amp or even a good cartridge!
Ditto 80stech's recommendation. The Dragon is the only cassette deck that automatically aligns the playback head to the azimuth of the tape being played - on the fly. Since 1/60 degree azimuth error is enough to deaden the treble response of a cassette tape, this makes all the difference.
I don't believe that any deck other then the Dragon had auto azimuth adjustment. Could I be wrong?
Manual azimuth is not that hard to use but I do think that the Dragon is the only Nak with auto, not sure of any others.