Generally speaking a GTX 1060 is roughly the equivalent of a GTX980 which is sort of the card that TANE was designed for.
N3V programmers use mainly nVidia cards so I'd stay within nVidia.
No matter what the card even a nVidia Titian (pascal) by carefully selecting the assets I can bring it to its knees in Trainz / TANE. Certain assets created in Sketchup have a lot of polys and textures. By the way the CPU is not nearly so critical, John Citron measured the temp of the CPU and GPU same scenario and in TANE the CPU ran cooler than TS12. So before you buy a whole new rig think about dropping in a GTX 1070, it will probably be cheaper and give you better performance than a new rig with a GTX 1060.
Cheerio John