This has probably been the most interesting post, thank you. So realistically, how much of a difference would this make to steam streaming etc, I can't think it would do too much if at all to this nature of work?
Congrats on that great deal with the GTX 1070!
Also for streaming they're all the same, bar raw FPS. The 1070 at the moment is faster in all games than the 480, so you got a great card.
For streaming Intel's QuickSync is better quality wise than both NV or AMD's alternatives; although it is a bit more demanding.
So in those cases the 1070 with better performance is still the best card out of the 3 you considered.
Especially with that deal you got.
I got a similar one on my Fury X, when I was looking to get the 480, and managed to get my FX for €80 more.