It’s battle of the big tabs. Literally. Apple has introduced the iPad Pro, following in the footsteps of the Microsoft Surface Pro 4. But which is best: the newcomer iPad or the more established Surface Pro?

On the (ahem) surface the concept of iPad Pro and Surface Pro may seem the same - they’ve both got “pro” in their titles, right? But they’re more different than they first appear: the 12.9-inch iPad being the slimmer, more tablet-like of the two; the 12.3-inch Surface Pro 4 being slightly thicker on account of its full-size USB port and more laptop-replacement stance.

We’ve reviewed both work-and-play-ready tablets in full, and having lived with them for weeks at a time here’s what we make of the two devices. Which is the best for you?

Size isn't everything but when it comes to portability it's definitely a factor for most. Especially as these two tablets aim to offer enough power to replace a laptop, it kind of makes being portable pretty high on the list of features.

The iPad Pro is the slimmer of the two devices, at 6.9mm, but it can’t offer the USB 3.0 port of the 8.4mm Surface Pro 4. There’s not that much between them. Indeed, both are as slender as many flagship smartphones of today.

The Surface Pro 4 is also the smaller of the two devices, with a 292.1 x 201.4mm front face compared to the iPad Pro’s 305.7 x 220.6mm. It doesn’t sound like much but, side by side, the iPad Pro really does look quite a lot larger. Think of it this way: the iPad Pro is about a centimetre larger in both directions than a sheet of A4 paper, whereas the Surface Pro 4 is the same width as the paper but a centimetre shorter.

In terms of weight, the 766g Surface Pro is a little heavier than the 713g of the larger-scale iPad Pro - but that all changes when adding accessory keyboards, seeing the iPad Pro become the heavier of the two. There’s not a huge amount in it, though.

Principal to each device is the operating system at their cores, which may be the key thing in your decision making.

Apple has stuck with its iOS mobile operating system, delivering the same experience as on any iPad, albeit at larger scale - so not the full OS X experience of a MacBook. Microsoft has gone down the full Windows 10 route, delivering the same OS as you’ll find on Windows laptops.

However, to say that Windows 10 is better because it's a full operating system, as opposed to the mobile iOS, would be to over simplify things. The use of each comes down to preference and, actually, what you intend to do with the devices.

Want to install full Photoshop? No problem on the Surface Pro 4, but not possible on the iPad Pro (although Adobe has developed specific tools to work with the Apple Pencil and iPad Pro, more on that later). On the flip side, Apple is more generous when it comes to those everyday functionality tools, such as Notes and Pages. For whatever reason Microsoft has failed to capitalise on its Office Suite by not pre-installing it on the Surface Pro 4 - you’ll need to buy an Office 365 subscription (£70/year), just as you can for the iPad Pro if that’s your preferred suite.

The biggest issue with a full operating system, however, is how much of a toll that has on battery life. Sure, there are additional considerations such as screen resolution and brightness, plus the processor choice - but the iPad Pro significantly outlasts the Surface Pro 4 in our tests.

For the record, we’ve been using the Intel Core i5 processor in our review Surface, which has delivered around 6-hours per charge with casual use. We fully expect the entry-level Intel Core m3 processor to lead to longer battery life, as it’s less powerful and doesn’t require a fan for cooling.

By contrast the iPad Pro comes with Apple’s A9X processor, making it 1.8 times faster than the Air 2. We’ve been getting around 9-hours of use from this arrangement - and while it’s not as powerful as the top-spec Surface Pro 4, it’s still the most powerful iPad ever and makes everything available on iOS run swimmingly.

So the choice is yours: the Surface Pro 4, with its desktop OS, is more powerful but shorter lived per charge, while the iPad Pro, with its mobile OS, is slightly less powerful but longer lived per charge.

The Surface Pro 4 has the slightly smaller screen at 12.3-inches, compared to the iPad Pro's 12.9-inches, with both offering almost identical levels of detail.

The Surface Pro 4 delivers a 2,736 x 1,824 resolution, the iPad Pro a 2,732 x 2,048 resolution - meaning 267ppi and 264ppi respectively. The iPad Pro has more pixels, it’s true, but the smaller screen size of the Surface Pro 4 means a slightly higher pixel density.

Between the two we can’t call it: they both look great in terms of colour, brightness, viewing angles and resolution. We prefer the Surface Pro 3’s smaller bezel surround, but if you want the larger scale display then it’s all about the iPad Pro.

The term “laptop-replacement” has been banded around aplenty, with both iPad Pro and Surface Pro 4, in part, being such solutions - with the right accessories anyway.

Neither the iPad Pro or Surface Pro 4 comes with a keyboard included in the box. If you want to buy one, the latest Microsoft Type Cover is £109, while the Smart Keyboard for iPad Pro is £139. Both double as protective screen covers; the Apple product can also be positioned as a stand - something not required for the Surface, given its built-in metal stand to the rear.

Of the two keyboard accessories, Microsoft offers more. There’s a trackpad built-in (40 per cent larger than the third-gen Type Cover), the keys are backlit, and, if you’re based in the US anyway, even a fingerprint scanner (sorry rest of world!). The Smart Keyboard for iPad Pro doesn’t offer such features and has five rows of keys rather than six - losing the quick command / F-keys and adopting a US-only keyboard layout.

Despite this, both are great to type on. The Smart Keyboard has a woven fabric coating that feels good to the touch and provides no gaps to the sides of the keys for a water- and stain-resistant finish - something the Type Cover can’t offer. Key spacing on both is just like a proper keyboard, so there’s no irksome re-learning of key placement if switching between a full-size keyboard or either iPad Pro or Surface Pro 4.

Here’s where things get really interesting. As both iPad Pro and Surface Pro 4 have touch-sensitive screens, both can benefit from the use of a stylus, known as the Surface Pen and Apple Pencil, pencil case fans. Microsoft includes the Pen in the box, whereas the Apple Pencil costs £79.

So, Pen or Pencil? Again, we really like both. The Pencil is a smaller, more slender design that’s uncomplicated and feels as close to a proper drawing implement as we’ve used in the digital space. It’s got accuracy down to a single pixel which can really be felt and seen, all depending on the virtual tips you choose and angle at which you come to the screen.

The Pen also delivers a strong show but, for us, feels more functional. It has an eraser button that doubles-up as a quick-access button, the nib provides 1,024 levels of pressure, and there are optional accessory nibs available (sold separately).

In terms of battery life, the Pencil has a Lightning connector on board, which can suck-up 30-minutes of power by connecting to the iPad Pro for just 15-seconds; fully charge it and it’ll last for 12-hours. By contrast the Pen has a built-in replaceable, not rechargeable, battery that is said to last for up to a year - then it’s a case of buying another when it’s depleted. Two very different ways of thinking.

The Pen also snaps against a magnetic side of the Surface Pro 4, which is now positioned opposite the charging side (unlike with the Pro 3 model). The Pencil doesn’t have a specific home on the iPad Pro’s body, so you’ll have to rely on carrying it separately.

So whether you’re an artist, designer, or similar, both options work well. For us the Pencil is the more natural to hold and use as you would on a canvas; the Pen feels more technical.

Apple isn't particularly well known for budget products. Yet in this case of the iPad Pro is slightly cheaper than the entry-level Microsoft Surface Pro 4 - with Apple’s 32GB option priced £679, compared to Microsoft’s 128GB (Core m3 with 4GB RAM) option priced £749. (Note, there's a microSD slot on the back of the Surface, but no such storage expansion on the iPad Pro.)

As the Surface Pro 4 comes with the Pen, however, adding the Pencil to the iPad Pro setup would see its price move to £758, positioning the two products almost neck-and-neck. And let’s not forget about the keyboard accessory costs too.

But where things get pricier is if upgrading the Surface Pro 4. If you want to really crank things up then RAM configurations up to 16GB, an Intel Core i7 processor option, and 512GB SSD are all available - opt for them all and you’ll be looking at £1,799, but will have considerably more power at your fingertips.

Given the similar pricing (at entry-level), is choosing iPad Pro or Surface Pro 4 a case of opting for a 12.3- or 12.9-inch screen? Nope, it’s more complex than that.

Reflecting on the two products we feel the iPad Pro is more large-scale tablet, whereas the Surface Pro 4 feels more like a laptop-replacement. The physical size and display resolutions are less significant than they seem on paper.

The choice of a full Windows operating system has obvious appeal for certain power users, yet the iPad Pro does still offer a strong catalogue of iOS apps - and you’ll know whether they include that essential CAD software or the like, thus sealing your decision.

However, the extra power of the Surface also comes at the detriment of battery life. You’ll get a full day from the iPad Pro, whereas the Surface Pro 4 will be left flagging.

So we’re left feeling as so: the Microsoft Surface Pro 4, with the Type Cover added, is the more viable laptop-replacement; the iPad Pro, while also capable as a laptop-replacement in part, is more large-scale tablet.

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