Recommended PSU for this setup?

[Joe!]

Hi there,

I am stuck between which upgrade to get for my PC, but I would like to know which of the following power supplies would be best suited to either build:

Core i7-5820k
Asus X99 Deluxe/MSI X99A Krait
4x 8gb of Corsair LPX/Dominator RAM
2x Gigabyte G1 Gaming GTX 980Ti
Corsair H110

Or

Core i7-6700k
MSI Z170 Gaming Titanium
4x 8gb of Corsair LPX/Dominator RAM
2x Gigabyte G1 Gaming GTX 980Ti

The power supplies in question:

Superflower Leadex 750W Gold
Superflower Leadex 850W Gold
Superflower Leadex 1000W Platinum

There's quite a price gap between the three, £100 > £115 > £150, so I am not too sure which to go for, I do plan to overclock, but nothing extreme.

Thanks!

 

[Joe!]

I was hoping I could get away with an 850w, the £30 gap at the moment (aiming to get the white version) is a bit daunting, but I suppose that's the cost of platinum efficiency.