Contax RX
A fairly new and electronically advanced manual focus camera with motor drive integrated, it has almost everything, plus the unique focusing aid within the Contax lineup. Unfortunately it has really slow response and works only for f5.6 and wider settings. Also there's a depth of field display in viewfinder, along which you can determine whether your object is within the DOF, if not at exact focus. Another nice feature is a low vibration system, which reduces camera shake and noise- in fact it's so quite that I couldn't believe it's SLR (around the noise level of Canon RT, which mirror doesn't flip, and probably less!).
Main complain about camera is the dark and small viewfinder (even 167MT is brighter), there's no way to add a vertical release, and the mirror return is much slower than the other two- then again this is not a professional camera. On the plus side RX has custom functions and programmable multiple exposure mode, also the data back comes with it imprints data between the frames too!
Nikon F3
Before I acquire a F3, I thought RTS II has a really nice finder, but I was wrong! The standard DE-2 finder is so great and there's nothing I've seen even close to it. My only complains with F3 are about the exposure compensation and lock, as stated before.
In comparison with Contax RTS II, I like F3 better, here's why:
Bright (not to mention 100% coverage) and fast-to-focus finder; it's also interchangeable. DW-3 Waist Level Finder is a worthy addition for those who like to do street photography, but I wouldn't recommend the DA-2 Action Finder unless it serves your purpose- it's heavy and makes the balance a little bit weird without MD-4 attached to your camera.
Lots of interchangeable focus screens. They are also extremely easy to change, you only need your fingers, no tools required.
Super build quality, mine works fine, but both of my RTS II have one or two problems.
Better ergonomics. It's easier to hold.
Smooth and effortless film advance mechanism.
Steeples shutter speed in aperture priority mode.
80/20 center-weighed metering (against 60/40 in RTS II) is more useful in my opinion.
Dedicated multiple exposure leveler.
Motor drive MD-4 is big, but when mounted, it can power the camera (180 rolls with alkaline-manganese battery), which is W-3 can't (the big W-6 can). MD-4 also fires up to 3.8 fps (V.S. W-3's 3 fps) with manganese battery and 5.5 fps if you can find the original Ni-Cd rechargeable battery. Although MD-4 doesn't have a vertical release button, you could find the MK-1 Firing Speed Converter that will give you the button, along with the capability to choose continuous shooting speed.
MF-18 data back is useful, since it can imprint data 'between' the frames and also automatically stops the winder when rewinding to leave the film lead out. I found the LOW (ISO) setting for Detla 400 is too strong, and you should use HIGH with Deta 400 @ both ISO 400 and ISO 800.
Contax RTS II
The first film SLR I've ever obtained, my first one came cheaply because it has an electric leak and eats up one $10 battery within two rolls of film! In the end I got another good deal so the older one became a backup.
The RTS II is around the same era of Nikon F3, and they are both designated as professional camera. With pretty much every function you need packed into it, it's a nice camera to use. In comparison with F3:
I like the LED display in the viewfinder, it really makes night shots much easier. F3 has a power-saving LCD display.
Easier-to-use exposure compensation, though some may say F3 has an advantage with the locking mechanism. However, F3 doesn't have the compensation mark display in viewfinder...
The real exposure lock, which locks the exposure value and changes accordingly with aperture setting. F3 only locks the shutter speed and you have to keep the button pressed.
RTS II has the same TTL hot shoe as we are using today, but F3 has the old ISO type.
As for the winder, Real Time Winder (RTW) is not exactly a good choice over W-3. Since W-3 offers grips, vertical release button, and compactness, the choice is obvious here. However, it's kind of stupid that you'll have trouble pressing the exposure check button with W-3 on (considering it's a Porsche design).