You're kind of all over a rather vague map...
You're
"looking for best quality sensors with great dynamic range and highly accurate color"—that leaves a lot to interpretation. What do
you consider to be
great dynamic range and
highly accurate color? You need to figure that out for yourself, especially when it comes to what appeals to you regarding color reproduction.
Next
you need to decide what
"I love the idea and price point of, say, the Fuji GFX 100S" and "I'm leaning more and more towards a Phase digital back" means
to you,
by trying some equipment for yourself. You need to find a way to get demos from dealers or manufacturers, borrow or rent equipment, and
decide what works for you.
"am I right in believing the Phase Backs are significantly superior, especially in real use dynamic range, than the Fuji's?" Which Phase One backs are you referring to? Which Fuji cameras? They're not all the same. Dynamic range compared under what conditions? Low ISO with bright sunshine and short exposures? High ISO and long exposure in low light? You need to build some personal experience in evaluating these things thru your own use.
The same applies to questions regarding cameras and lenses. You seem to be looking for the best compromise between light weight and mobility and optimum image quality. The best compromise for you is not necessarily the best compromise for numerous other individuals online or elsewhere. It's something that you discover by personal experience. Then there's that budget thing which only you know because you've only made vague references to having one.
"Photographers to reference: Richard Misrach, Ed Burtynsky, Simon Roberts. Lot's more I could reference, but these three are the closest in terms of the way they shoot, the equipment they use and the way they want viewers to experience looking at their work." Here's what I can tell you about your references,
"the way they shoot" and
"the equipment they use" was gained thru their personal experience and use of a very wide range of equipment — and to show that I'm actually trying to assist you, I'll provide some links to interviews and quotes from them for you to peruse.
Here's a quote from
an interview with Richard Misrach: “The work in the show, which spans 40 years,” Misrach notes, “has been made with a number of cameras: in the 1970s a Hasselblad and a slightly wide-angle lens; an 8×10 Deardorff view camera with a normal lens (1980s to around 2005); a Hasselblad and a telephoto lens (2005 to the present); and an iPhone.
The pictures look the way they do not so much because of the camera I use, but rather because of where I set up and shoot in relation to my subjects.”
Here's an interview series with Ed Burtynsky from Luminous Landscape in which he discusses equipment choices at various stages of his career and the evolution of his shooting style at some length.
An Interview with Edward Burtynsky – Part 1 of 3 [evolution as an artist],
Part 2 of 3 [evolution of equipment choices],
Part 3 of 3 [printing and other output]. You will likely enjoy this series of interviews as he covers in detail much of what you seem to be most interested in discovering. He talks at some length about his evolution from 4x5 and 8x10 film cameras to the present using a Hasselblad H6D-100c. I hope that you find some inspiration and insight.
For any photographer or other artist producing interesting work,
"the way they want viewers to experience looking at their work" is a personal vision developed over time; drawn from and expressing
their inner thoughts and feelings about
their subjects. That's what artists generally strive for in their work. Imitation of an artist is one way to build some knowledge of skill and craft and a well from which to draw some inspiration. Once acquired, it then needs be turned into your own vision.
I've probably given you nothing even remotely close to what you're looking for, but best of luck to you. Enjoy
your journey.