I have an iphone 4s and I'm debating whether to get the Iphone 5s or the 6?

I personally like the look and design of the 5s better, and from what I hear, screen size and size in general are the only big differences between the two phones. If I were to get the 5s, I would get my dad's current phone b/c it's only a few months old, and he would get the 6. Then I would be able to get the 6s when it comes out, because his contract would be up by then. What do you think?

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