If they were priced the same, I'd go for the 2017 with the Ultegra crank. To actually save $500 would make it a no-brainer for me.
The 685 levers have always been considered Ultegra-level, though not specifically branded as such by Shimano (whereas the 505s were considered 105-level), so I'd consider levers/calipers to be a wash.
I'd prefer a Shimano crankset vs not and, in addition, my (not at all comprehensive) understanding of the mechanical differences between 6800 and 8000 cranks/FDs is that the spacing between the small and big ring is a little tighter on the 8000, so I'd be concerned that the spacing on the Oval is appropriate for the FD.