The Makina is a great camera. The main failure with it concerns the meter, which is a built-in flaw of the construction. The meter is not too useful anyway IMO.
Sometimes I read about the transport mechanism which was apparently up for improvement in the 670 which followed the 67. Key is that the camera was handled with care.
I had a 67 which worked and it was a pleasure, very sharp, nice saturation. Only downside is the shutter release: it does make you move the camera downward, even if ever so slightly.
If the price is not different, I would now go for the Fuji/Bessa 670. For what I've seen, very nice camera, bokeh no better or worse, and it will be 30 years newer.... And you have the choice between 6x6/6x7, Plaubel is only 6x7.
Plaubel do still service their old cameras, but at a (substantial) cost.
I have heard warnings about repair of the Mamiya 6 because there are no longer parts available. Not sure how true this is. You may want to ask a local(-ish) repairer of repute if s/he has any parts, etc.
BTW, it's not a rangefinder, but I was surprised as to how little different in size my Rolleiflex was compared to the Plaubel.
I own a Makina 67 and do like especially the meter with its spot-meter functionality: The measurement spot is identical to the rangefinder spot in the center of the viewfinder. Using it on the right "18% grey" parts of the subject results in exact exposure - important in particular for slides.
I am actually fancying a 120 RF to compliment my Rolleiflex! I love the IQ but I want something faster to shoot and at eye-level...I have Leica M's but I sometimes find the IQ lacking.
If faster is what you're after, I would not take a folder (which you need to handle with some care). The Mamiyas 6 or 7 are a more logical choice in that case.
My lightmeter in the Makina 67 certainly was not as precise as described above, but maybe I was unlucky.