Perhaps you should install Rhino 6 and check new viewport speed improvements.
Then check this infos:
You can download WIP file and have a test for your self inside your machine.
Personally I think Quadro Cards are mostly smooth on work with many polygons, meshes and triangles. Also they handle better multiple external monitors and color accuracy.
And if your render engine is mostly Raytraced like Vray, you dont need as much CUDAS, Like GTX Ti or Titan X Pascal.
I think you need a fast and smooth transitions between working inside viewports, rotate objects in many viewports with multiple external displays and multiple softwares read multiple viewports in multiple monitors.
Here at my office I work with a Gigabyte GTX 1080 and honestly this gaming card is a complete shit. It work fresh but sucks… Nvidia only produce performance drivers for games. OpenGL and Point Precision in this segment gaming cards are real shit. (sorry this words).
My other computer in office have a old QUADRO K2200 and i can`t tell you the difference. But one thing i can say is this K2200 old card can handle much better a Rhino file with a Master Plan plus many trees and a lots of external linked files. Rotate is like butter. Antialiasing is smooth and so on…
But if you have a render engine that work with CUDAS, like OCTANE render, THEA Render, ARION render, which is a fast render preview and stable ones, than i have to say to choose the most powerful GTX in the market. Or buy 2 GTX less expensive in SLI (2x GTX 1070).
If your render engine is calculate final renders in CPU, go buy the best most thread CPU on the market if possible. Many Cores and threads helps a lot in final render. Check Ryzen 7 (1700x or 1800x or Threadripper 1920x)… or choose a Intel, like 8700K, 7900X, 7820X (6 cores up), but you dont need to spend to much money. Unless your work profit will pay you your machine like in 2 works or so.
If your render Engine loves CUDAS as i mentioned, go buy GTX as much your can. GTX ti, Titan etc… But if you use Vray just use CPU for final renders. GPU render in Vray is no stable yet. Not full working. Still need a lots of improvements.
So perhaps you should be fine with some specs like this:
64Gb Ram DDR4 2400Mhz
Good AMD Mobo
64Gb or 128Gb Ram DDR4
Good Mobo (like AsRock Taichi)
64Gb Ram DDR4
Quadro P4000 or GTX 1080 Ti or Titan X Pascal
128Gb Ram DDR4
Very good Mobo Asus Worksation class.