This is a rough guideline showing modern GPU sweet spots for different resolution in modern titles. The sweet spots may vary depending on the situation.
1080p @ 60hz = RX480, GTX 1060
1080p @ 144hz, 1440p @ 60hz = GTX 1070
1440p @ 120+Hz, 4K @ 60hz = GTX 1080
I recommend the g4560 kaby lake route over the i3 6100 Skylake route. The G4560 is only slightly less powerful than the i3 6100. The kaby lake is a bit cheaper (~$25 USD) when including the price of a b250 motherboard (to support for kaby lake) compared to an h110 motherboard + i3 6100.
You will also receive the extra benefits/features of a b250 motherboard as apposed to an H110. The kaby lake option does support for 2400mhz ram, unlike the Skylake option, which can make a small impact in games.
However this does depend on what you intend to be using the processor for. In some tasks where hyperthreading isn't supported, the i3 6100 may be the clear winner.