Should I get 6s or 7?

So I'm looking to buy an iPhone and I was deciding between 6s or 7. I'm going to get another in 2 years anyway but I was wondering if it really worths paying more to get 7 or will 6s be good too for like 2 more years. I mean updated and everything. I heard it's a good phone anyway. Any suggestions?

Always get the latest and best you can afford

If you are looking to save money now, the 6s would be fine. The 7 of course is better but both phones would be still receiving updates in 2019.