Should I upgrade to the iPhone 6s?

I have the iPhone 6 and suffered from "bendgate" my phone works but it's slowly falling apart at the seams. Everything works on it but I don't know how much longer it will. I won't get anything else but an iPhone but I was thinking would it be worth it to upgrade? Or downgrade to a 5s? I will not get another 6 because of design flaw

Why a change? Even after you know why it bent, are you still convinced that you're going to bend it again? Normally this is an issue for someone ONCE, because they just don't sit on it again.

The 6S is made from 7000 series aluminium which is aircraft grade aluminium and is 3X+ stronger than the iPhone 6, it also has Dual ion X glass which is the strongest glass on a phone currently. Apple also made the phone water resistant, they don't officially claim so but in tests the phone can be left of up to an hour in water and it'll be fine.

You could check an Apple Store about getting it fixed and or trading it in towards the 6s.

I would get 6S, your 6 should still be worth alot on trade in.