This depends on your money.
SS7 is good product in a few years later. In my opinion, just buy it.
I have had a samsung galaxy note 3 for about 2 years and it has worn down a lot. Ive been wanting to get an s7 edge, but I've been reading and hearing good things about the galaxy s8. Should I wait the extra 5 or 6 months for the s8, or should I go ahead and get the s7 edge?