I'd rather an iPhone personally.
I don't really care for Iphones at all. They are over priced, too sand boxed and very short on custom-ability. They also fall short on some development cycles. That said, i understand why some people like them. I have family members who would be lost with an android. With power comes additional complexity and sometimes a simple phone works better for more people. And they do have some good characteristics (Like a great camera). But I enjoy a more flexible & powerful phone at a reasonable price.
Here is a review I found comparing OnePlus 3 vs Apple iPhone 6s
http://www.stuff.tv/features/oneplus-3-vs-apple-iphone-6sIt seemed to be a fair & thorough evaluation.