Out of 9 Marantz 70's recievers I have owned, the very best in sound-sonics I felt was the absolutely mint 2285B Black Face Euro version I owned. (and also had the matching 5025 Casette)
Dummy that I was to ever sell this pair, which I did about 4 years ago, and I did donate pictures of this pair to Ben Blish's Classic Marantz Site. They are still pictured there to be seen.
I owned two 2330B recievers (both mint) and IMO, neither had the quality of sound of the 2285B.
Also owned a bought new 4400 Quad reciever back in the day, it was a cool looking Unit, with its built-in CRT for sound display, and Radio Tuning, yet somewhat unorthodox compared to other Marantz Recievers of the day, with its Square Buttons versus all the rest using IMO prettier Round Function Buttons.
The CRT Blew 6 months later, and I dumped it for Macintosh Gear. This could be a monkey wrench buying, as once the CRT goes, you lose tuning capability.
While looking cool, the CRT offered no sonic benefit.
Another fine Reciever I owned, and again regret selling, was a mint 2265 I scored off ebay some years back for $100. This I felt came in second right behind the 2285B. Others, like the 2238B were nice for the smaller offerings, but no cigar against the 2285B.
Yes, there are more exotic, rare models out there which will set you back some serious change in today's market, such as the 2385B, the 2500, and 2600, and while I've never personally heard any of these three, I have read other owner's comments about the 2500-2600, and they weren't exactly totally thrilled by their sound compared to some of the other Marantz recievers. Both I believe also used rear mounted Fans.
While Sansui isn't perhaps as highly sought after, nor as pretty as the vintage Marantz, many times I preferred the Sound of the Sansui, with Units such as the Sansui 7000, Sansui Seven, Eight, and Eight Deluxe.
I've personally owned all of these, and all are absolutely kick-butt Recievers, exhibit very good clarity, and a sweetness of sound that many Marantz recievers just didn't duplicate. All were built like Tanks, and as others here know, didn't require optional Wood Cases like the Marantz.
Others. such as the 8080, 9090, 9090DB, G-7500 were said to also be very fine sounding Units, and as far as bang for the buck, these few will both nicely fit the bill as being very tough to beat sonically for the money. Hope this helps, Mark