The responses on here are HILARIOUS. No one has bench marked Apple's version of the A15, nor do we know the specs, but what can be said about it, it should be better than the A9 right?
Of course, but I'm not sure how much.
If history is a guide, and it is, Apple's version won't be the best processor on the market.(They constantly underclock to improve battery life). My money would be on Qualcomm, they have been killing the market for the past couple of years in designing quality low power consumption mobile chips. Their SoC technology, "Krait" is phenomenal to say the least.
Samsung also has an A15 chip being released in the new Galaxy Nexus and possibly the Galaxy Note 2; the Exynos 5 Dual 5250. However, will either one of these chips outperform the S4 in real world applications? We'll see.
The Galaxy SIII U.S. versions have the Snapdragon S4 btw.