I see the price as being about $100-200 less than an iPhone, but with a worse screen, slower processor, worst camera, and, of course, without the ability to take 9 years of paid content with me. No thanks.
Larger screen, equal resolution, better camera. Probably equally impressive processors... I don't know the SnapDragon 820 vs the A10 Fusion. Double the RAM means the processor has more to work with on the OnePlus 3 though.
And that's if you're getting a top-of-the-line iPhone.
Also, the price is $570 cheaper for the OnePlus 3.
Compare to a regular iPhone 7...
Larger screen, better resolution, better camera, significantly better battery, triple the RAM.
And it's $450 cheaper there.
And the battery on the the thing is ridiculously good. 30 minutes on it's Dash Charge and I've got enough power for 3 days. I find my battery dying simply because I forget that I have to charge the thing at all anymore.
Why would you compare the most expensive price of the iPhone to the cheapest price of the OnePlus (meaning, the MSRP which I cannot find anyone charging for it...retailers seem to be charging $20-150 more for the MSRP. So, again, for very little more money you get a ton more quality plus, for people already using the iPhone, they get to keep everything. This is a no-brainer.