Over the past several weeks of running the Samsung Chromebook with its Exynos 5 Dual SoC that is comprised of an ARM Cortex-A15 dual-core processor, I've grown quite fond of this latest ARM processor.
In the compiler benchmarks and extensively comparing it to the NVIDIA Tegra 3 and Intel x86 CPUs, the ARM Cortex-A15 has held its grown and competed very well. The A15 blows away the older Cortex-A9s and ARM's claims that it's 40% faster core-for-core clock-for-clock than the A9 is not just marketing fluff.
The Exynos 5 Dual is clocked at 1.7GHz with two cores while I'm quite looking forward to NVIDIA's Tegra 4 "Wayne" that will be quad-core up to 2.0GHz when they debut early next year along with a better NVIDIA GPU integrated onto the SoC. There's also the Texas Instruments OMAP5 chips that are expected to run at 2.0GHz but will be packing just two cores and sticking to PowerVR graphics.