The iPhone 6S also has 3D Touch, which adds a new way to interact with the phone, allowing it to respond differently to light and hard presses. It's a bit like the way you can get different options by tapping or long pressing an icon on many handsets, but with it records pressure instead.
The OnePlus 2 doesn't have any fancy pressure sensitive tech, but it does have a pretty great interface. It runs Android 5.1 skinned with Oxygen OS, which keeps the Android look and layout but adds a bunch of extra options, such as being able to launch the torch or camera by drawing a shape on the screen.
At 3,300mAh the OnePlus 2 has a larger battery than most 2015 flagships and it lasts a little longer than many too, comfortably seeing you through a day even if you push it a bit, but it won't likely last through a second day or even a second morning.
The iPhone 6S probably won't have quite as good battery life, as we're expecting similar performance to the just-about-a-day life iPhone 6, but we'll let you know when we've properly put it to the test.
Price and availability
Price is one thing the OnePlus 2 really has going in its favour, as you can pick it up from £239 ($329, around AU$517). That's ludicrously cheap for a flagship phone, but sadly actually buying it is a little trickier, as it's invite only.
The iPhone 6S has the sort of price you'd expect from a flagship, starting at £539 ($649, AU$1,079). In other words it's almost double what the OnePlus 2 costs, but it is arguably a slightly more premium phone.
You won't need an invite to buy the iPhone 6S, but stock may initially be limited given the huge demand for it.
The biggest thing the OnePlus 2 has going for it is its price tag, as it's hard to justify paying almost double for the iPhone 6S. Price aside the OnePlus 2 is pretty great too, thanks to flagship specs, a good camera and an improved design.
That said if money is no object the iPhone 6S looks like it could well be the better handset, with a more premium build, a likely better camera and innovative features such as 3D Touch.
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James is a freelance phones, tablets and wearables writer and sub-editor at TechRadar. He has a love for everything ‘smart’, from watches to lights, and can often be found arguing with AI assistants or drowning in the latest apps. James also contributes to 3G.co.uk, 4G.co.uk and 5G.co.uk and has written for T3, Digital Camera World, Clarity Media and others, with work on the web, in print and on TV.