I have owned the Contax 139 and a couple 167 MT's. I have handled the RTSll, Aria and also various Nikon bodies. To me the Contax cameras were much more ergonomic than the Nikons. Of course this is a personal preference. As far as durability both Contax and Nikon were great. A fellow I knew at the local pro shop told me that the biggest problem with any brand of 35mm cameras was the manual film advances jamming. The 167 MT solved this with built in motor advance.
You can't beat Zeiss lenses but of course Nikkors are not bad either. :)
I would take a Contax camera over a manual focus Nikon camera any day. I own a ST, 139 and a Yashica FRI. A previous poster had the #s wrong for the FRs. You want the FRI. The FRI is a little more old school, but I have been beating on mine for 20 years without a hiccup or service. The 139 is a classic small camera. If you want more automation then the later bodies are nice. I really like the ST. It is like the little brother of the RTS III. The RX is another good body. The RTS III is of course the flagship, but it is rather large. The S2 has been mentioned, and it is one of the best all manual cameras. I would love to get one someday, but they ain't cheap.
The following models have matte screens that can be installed according to a system brochure I have from the 90s- RTS II, RTS III, ST, RX, 167MT, S2, 159MM.
I hope that helps you. If you want the system brochure, p.m. me with your email.
Yes - a plain matte screen is available: the Contax FU-5 and if you shoot architectural photos, they have a sectioned matte screen FU-6. These screens are widely available, especially on Ebay, as they were made to fit 4 different models (167MT, S2, S2b and Aria) and were manufactured right up to the end.
I have used Contax RX, AX, RTS, RTSII and Yashica FX-3. Also have used Nikon FM2, FE2, N70, F3 and F2. By far the best built by my own subjective use are the RTSII and F2. Though none are anything I'd call slouches. I stick by my recommendation of the RTSII and 50/1.7 Planar. Probably be less than $300 total for both. Great kit.
Nothing beats the Aria and the 50mm1.4 Zeiss combo except maybe the RX 50mm1.4 Zeiss.
I have had 167mt, RX, G1, G2, and RTS III bodies in the Contax line-up (the G-series of course being the autofocus rangefinders). I loved them all, with the RX probably being my favorite. I now have an RTS III, which is an incredibly sophisticated camera for something from the late 80s (1/8000th top shutter speed, 1/250th flash sync, TTL flash metering for non-dedicated strobes (I know, wow!), and perhaps most famously, the vacuum film plane. This is NOT the camera for someone who values battery-free operation - it needs 6 AA batteries and without them is pretty much dead in the water. But you get all that goodness mentioned above, plus a 97% viewfinder (97% of the film area is visible in the finder - very important when shooting things like copy slides or macro work where composition is critical). Back in the day they were $2200. Now, one in pristine condition will run you $800, or if you're patient, you can find one with a few cosmetic blemishes but in good working order for <$500. And to top it off, if someone tries to mug you, you can beat them into submission with it.
Contax bodies are great when they work; my first camera was a Yashica FX-D (poor mans 139) and a 50 1.4 Planar (loaned to me from my father when I was 8 years old)
OTOH, Nikon bodies are way more reliable and the Planar may have been updated in the ZF configuration and thus "better"
Going with C/Y cameras does open you up to the entire C/Y catalog
Look at an F3, too. Not mechanical, but you will not be able to kill it unless you hit it with a sledge. I don't believe the same can be said for any postwar Contax.
Up until a few months ago I had a FM2n with a Zeiss ZF2 50/1.4 and the plain matte screen (I believe it was the B2, got it for $10). It was a fantastic combo, I loved the Zeiss glass and the screen was really good for focusing, no problems with it and always bang on focus anywhere on the frame. I have no experience with the Contax bodies so I can't help you there. If you go down the Nikon route you can save some money by going for the first generation ZF lens (which doesn't have the electronic contacts) instead of the ZF2 which you don't really need for film bodies.