The Exynos CPU is definitely the better of the two, from all accounts I've read it's the more stable, has better heat management and, arguably most important of all, has by far the better battery life. The Snapdragon variant has a better GPU, but in real world use you won't notice any difference and you will pay for that additional performance with excess heat.
To begin with, I was disappointed not to be getting the more flexible Qualcomm SOC, as it's open source so AOSP and CM based roms would be far easier to cook. However, even ignoring my points above in the first paragraph, all Snapdragon S7/S7 Edge phones have locked bootloaders, meaning they can't even be rooted on stock, never mind have a completely custom vanilla Android build flashed.
No, we definitely got the better deal with Samsung's own SOC.
