Then either of those builds will be awesome for you.
The i7, as I mentioned is probably a little overkill - but hey, there's no harm in that.
Personally, I'd opt for the i5 + 1070 setup for 1080p/144Hz gaming, but the i7 is a powerhouse of a CPU too.
Supahos :
You do realize you're backwards on your i7/i5 4kvs other resolution. The i7 is a better idea trying for 144hz at 1080p or 1440p an i5 is more than enough for 4k. The processor doesn't care what the resolution is only the GPU.
No, I'm not backwards there at all. The i7 will show gains in some titles at 4K, and in others, will perform near identical to the i5.
It's not just the GPu that comes into play at 4K, the CPU (depending on the title, of course) can play a big factor too.
At 1080p, the i7 will have zero benefit vs an i5 (and depending on specifics, the i5 may well win out).