Probably worth mentioning that the EVGA Z87/97 FTW, when operating with all four x16 slots filled, runs at x8/x4/x4/x1, while the Gigabyte GA-Z87X-OC and GA-Z97X-OC run the four x16 slots at x8/x4/x4/x4. I believe both boards run the final slot at PCIe 2.0 spec rather than 3.0.
Not sure how important it really is to the OP (as they mentioned maybe being okay with an x1 slot), but just thought I should mention it.