edit: To clarify, I mean this because the A7 is a custom design that just happens to be fabbed by Samsung under contract, rather than an off-the-shelf component, like the M7, that has simply been granted a marketing buzzword. Other OEMs will not simply be able to integrate the A7 in their products for this reason.
"Does Apple use any components which are best-in-class and unavailable to competitors?"
The answer there is "yes", at least according to a bevy of evidence from the AnandTech review/benchmarks: http://anandtech.com/show/7335/the-iphone-5s-review.
edit: To clarify, I mean this because the A7 is a custom design that just happens to be fabbed by Samsung under contract, rather than an off-the-shelf component, like the M7, that has simply been granted a marketing buzzword. Other OEMs will not simply be able to integrate the A7 in their products for this reason.