The Best A15 chip to wait for

I've got the Nexus 4 and now there will be a deluge of A15 based phones. Obviously an update is imminent, so I was hoping to find out which out of the A15 chips to buy a phone for? Exynos Octa, Tegra 4, Snapdragon 800. Please dont turn this into a brand loyalties war. There are way too many articles adrift on the internet about these chips but none of them seem to have all the facts.

P.S. Do mention anything you know about the GPU performances as well.