The A7 seems pretty exciting to people who pay attention to these things: http://www.anandtech.com/show/7335/the-iphone-5s-review
The CPU? ARMv8 isn't a thing, it's an instruction set specification, just like x86, implemented by various micro-architectures. Samsung doesn't do that (yet).
Apple's implementation is very much something to steal, given that it outperforms everyone else's.