"The best colour rendition" is subjective- some like it warm, some lie it cool and some lie it neutral. Aside from significant shifts and extreme biases, who is to tell? To what standards would you base your assessments? Neutral white and blacks, any particular muting or exaggeration of specific colours? There are also many variables such as exposure, colour temperature of the light sources, and more.

Surely there are differences from one camera's make and model to another as to colour rendition and various lenses may have unique colour responses of their own. Without having access to a wide variety of cameras and lenses and performing laboratory-grade tests on each wonder high controlled conditions with the use of precise instrumentation, again who could tell. Under practical and everyday shoot circumstances under a wide scope of conditions, it's all personal perception, taste. and artistic judgement as to the colour rendition's appropriateness to the scene or subject.

As others have alluded to in the film era,photograher selected transparency films, colour-wise, as to their "palette". Certain films had particular biases, could mute or exaggerate certain colours and other properties such as contrast and saturation were also considered. In a digital camera, you are confined to whatever the engineering of the sensor and system has to offer and the final disposition of colour balance, rendition saturation, brightness and contrast are tweaked, altered or perfected as the photographer's taste and perception in post-processing.

Colour-negative films also have certain biases and unique colour characteristics, but again, the final colour balance and rendition are finalized in printing.

Straight out of the camera? So, how do you view your images? Do you print or just enjoy them on a screen? Whatever tasks place from the time the image leaves the camera and goes to the screen or the printer also influences the colour rendition. Is everything perfectly calibrated? I am not a big fan of super-manipulative and complex post-processing, except for special effects, but I can not imagine how anyone who is critical about colour rendition can do with ANY post-processing. Sample post-processing gives the photographer full control over colour balance, contrast, saturation, contrast and brightness. Those are all the essential properties of colour rendition.

I have used a wide variety of cameras and lenses over the past nearly 60 years. I have found by practical experience, not by exhaustive testing, that most modern lenses, especially nowadays are high corrected for the aberrations that can affect colour rendition. I have used cameras made by Hasselblad, Canon, Nikon and a few others and have never found a colour rendition that I could not easily correct or customize. In the digital age, cameras and even cell-phone cameras are being improved, as to colour accuracy, by leaps and bounds seemingly on a monthly basis.

I don't like bragging, but when I ran an analog/chemical colour lab in my studio, I could see colour variations to a .005 filtration. I did custom printing for years and drove some of my technicians to drink!

There are always differences between mfgrs, and even between models from any given mfgr. None are accurate ie true to life right out of the box. I use an Xrite ColorChecker Passport to build a profile for the camera when accuracy (color fidelity) is important. The process is based on the raw capture, and the result is color neutrality - regardless of camera brand or model. I have used it when employing a second shooter with a different camera from mine and I need to have the results look as if it were from a single camera when they are presented to the client.

Plus - Since everyone's eyes (and mind) perceive color differently, what IS reality???

A calibrated monitor you say? But what if my eyes don't see the "reality" the way the monitor displays it.
I wonder if anyone's 'calibrated monitor' looks funky to them.

And - Everyone intrinsically thinks that if they see a certain color a certain way, everyone else will see it that way also. Now think about two, three, four, five, plus colors in an image...
Possible, but highly improbable.
Just HOW different between people? We'll never know.