No question that both are good phones. Depends what you value more
1) Galaxy s7 edge has the 5.5 display in a reasonably compact body, great battery life, great camera, wireless charging, micro sd card slot, waterproof, NFC with android and samsung pay
2) Pixel XL Great camera, amazing speed and promise of best software updates
lots of bleeding edge features like google assistant
great screen
good battery life
usb c port
Google daydream compatible
but again
no wireless charging
no micro sd card slot
not waterproof
super expensive
nfc android pay only, no samsung pay
larger in hand than the galaxy s7 edge, a bit clunkier to hold (for me)
I had just invested in some wireless fast charging stations from samsung, and to reduce stress on the micro usb port I thought this was useful. No such option on the pixel or pixel xl
I really wanted to keep my pixel xl, but it was hard to justify the expense of the phone when it was missing so many things common to smart phones in 2016, mainly water proofing, stereo speakers and expandable storage.
so I returned my pixel xl and kept my galaxy s7 edge. I don't think you can go wrong, its just a question of which is more useful.. I'd rather have the microsd card slot, waterproofing and wireless charging than a half-baked google assistant or other software features that are coming along slowly...there is a price to be paid for being on the bleeding edge...
Losing the micro-sd slot was tough for me, but no waterproofing? Meh. Even the htc bolt has it now!