The 1070 is still a respectable card, and G-Sync is good to have.GTX 1070...would the benefits of the faster card be worth it over the benefits of G-Sync?
I went from having freesync monitor and an rx580 to a 1060 and really missed the freesync. So much so that I went back to amd just for the freesync itself.
If you're tied to your monitor that much, maybe it makes sense to use the G-Sync features and stick with Nvidia. *I am a freesync user that prefers amd junk.