We love the Surface Book. We love the Surface Pro 4. But what we haven’t told you yet is the question many of you are asking: Which one is better? And the answer is: the other one.

For the last week, we’ve tossed the question back and forth: which one do you like? Why? We both agree that the Book’s appeal lies in its discrete GPU, battery life, and laptop-like form factor. The SP4 is slightly cheaper but offers some serious bang for your buck. Gordon and I know both devices: I spent time with the Book, then tested the Surface Pro 4. Gordon owns a SP3 and wrote our Surface Book review.

But a funny thing happened on the way to publication: Each of us became convinced that the other Microsoft product was better. I’m sold on the Book’s long battery life, and Gordon was more partial to the sharp uptick in performance the SP4 offered—without all the cash you’d have to lay out for the Surface Book. So here’s what we decided to do: make our case for each product, and let you decide who’s right.

But yes, we still picked a winner.

Features

Mark: For me, the debate’s almost over at this point. The Surface Book is simply the sexier of the two machines, with that articulated hinge, gorgeous 13.5-inch 3,000 x 2,000-pixel display, and detachable tablet. I can see little wrong with the device, save for the fact that the “clipboard” tablet lacks an expansion slot. Walk into an airport lounge or coffee shop with a Surface Book, and everyone knows you mean business. It’s Microsoft’s Chromebook Pixel, but it can actually, you know, do something.

Gordon Mah Ung The hinge on the Surface Book is more than pure bling, Microsoft says. It keeps the entire laptop from flopping over.

Don’t get me wrong—I love the Surface Pro 3. That thing’s lived in my backpack for most of last year, and finally cracked under repeated use. (Speaking of cracking, the Book’s hinge should withstand a normal backpack load, Microsoft says.) The SP4 should step right in as a terrific replacement. But I can’t exactly pine for a minivan when there’s a Ferrari on the lot, you know what I mean?

Gordon: There is simply no sexier laptop today than the Surface Book. That beautiful, large screen and battery life and its performance really make it my go-to device for just about everything. But it ain’t small by a long shot. The Surface Pro 4 is something you don’t mind hauling everywhere with you every single day, while the Surface Book will make its presence known in your bag. And if you think “hauling” means walking from your cubicle to your car and tossing the bag in the trunk, I mean trudging or cycling miles with everything on you.

That’s why I think the Surface Pro 4 is the device for people on the go all the time. You’re getting a real computer with the productivity of a laptop but the footprint of a tablet.

Performance

Mark: For me, any discussion of a mobile device begins and ends with battery life—the best computer in the world is worthless if it doesn’t have power. The Book offers 13.6 hours of battery life; the Surface Pro 4 offers just over 8. No, the SP4 isn’t shabby at all, but you know how battery life tends to dwindle down over the life of the product. Journalists endure the CES test—a day that begins at 6 a.m., ends at 2 a.m., and involves frantically racing around and filing stories, images and video, often without a power outlet nearby. In such an environment, I want great heaping handfuls of battery life. The Book delivers in spades.

Man, look at the gorgeous battery life number the Book puts up.

I know the Surface Pro 4 doesn’t offer the graphics performance of a gaming notebook, or even a midrange laptop with a discrete GPU. That’s fine by me. I can run Crysis 2 on a Surface Pro 4 at resolutions and frame rates that make Original Gamers turn away in embarrassment. I ain’t proud. But the Surface Book gives me a decent discrete GPU that does it one better. And wouldn’t it be a nifty trick if Microsoft decided to sell a Dock with an external GPU, or just a better base? I think the future’s pretty bright for the Book here.

Gordon: There’s no question the Surface Book’s GPU option smokes the competition. And I mean all of the competition—not just the Surface Pro 4. But if you look at the CPU results, the Surface Pro 4 hangs right there with the Surface Book on just about any task that doesn’t stress the GPU. Intel’s integrated graphics has really come a long way. Even more impressive is the performance of the Surface Pro 4 over the Surface Pro 3. My biggest gripe with the Surface Pro 3 was how the performance fell off when it got hot, as well as the fan noise just running Chrome. The Surface Pro 4 fixes both issues.

The discrete GPU inside the Book gives it an edge.

I do wish Microsoft had aimed a little higher on battery life, as parity with the Surface Pro 3 wasn’t exactly aiming high. One thing I’d add though: The full story on Surface Pro 4 isn’t written yet. We pretty much know how all the iterations of the Surface Book will perform in battery life and CPU and GPU performance. The highest-end Surface Pro 4 will actually feature Intel’s Iris graphics, which should give it a very serious improvement in performance, while the lowest-end Surface Pro 4 will feature Intel’s power-sipping Core m3 chip. So Surface Pro fans, stay tuned—it may very well give the Surface Book more of a challenge.

User experience

Mark: You know, I staunchly defended the Surface Pro’s “lap-ability” for a while now. And yes, it’s competent. But the Book is a real laptop, one that properly rests on your lap—but doesn’t toast your thighs, either. And the Book just barely reclines far enough that it’s comfortable for me to use.

Rob Schultz The Surface Pro 4’s narrow kickstand is fine for a desk, but it’s still not terrific for prolonged lap use.

I carry one or two or three or four devices around with me on occasion for various reasons. I’m a hoarder. I have a problem. The Book is a solid two-in-one that can help me knock that habit. I just need to keep that Pen on a lanyard around my neck or else it’s going to be eaten by my backpack. I just know it. (Ditto for the Surface Pro 4, to be honest.)

Gordon: I decided “lap-ability” on the Surface Pro 3 had a ways to go when it flopped off my lap onto the carpeted floor no fewer than three times at the same conference. The reporter next to me had his laptop out and his Surface Pro 3 in his bag so yeah, not the greatest strength of the Surface Pro line.

But outside of those times I’m crammed into a seat that would make a budget airline blush, I’ve been fine with the Surface Pro. It is no by means a laptop and even I admit the Surface Pro 4 can’t touch the Surface Book. The gorgeous screen, the great keyboard, the giant trackpad...yeah, I got nothing here.

Bang for the buck

Mark: Can we just skip this one? Let’s just ignore the fact that Microsoft loaned us these tablets for review, so I don’t have to justify to my wife that spending $3,000 for a two-in-one when we have other laptops that do exactly the same thing is a good idea. Or that yes, I could buy a much cheaper Surface Pro 4, get my butt to a conference a bit earlier and sit next to a power outlet instead of checking out the complementary breakfast.

Peter Ruecktenwald Microsoft’s Surface Pro 4 easily tops the Book for bang for the buck.

So, um, I have to concede here that the Surface Pro 4 wins this category hands-down. Can we talk about the display again, though?

Gordon: Not to rub it in, but the base level Surface Pro 4 with its Core m3, 4GB of RAM and 128GB of storage will do the job for what 85 percent of people need out of a portable device. It’s also just $900. There’s a lot of fancy features in the Surface Book and you pay for it, too.

In the Surface Book’s defense though—I know, I’m crossing lines—premium features demand premium prices. No other 13-inch Ultrabook gives you this kind of graphics performance, run time or tablet functionality.

Conclusion: Money talks

You could argue that the Surface Book and Surface Pro 4 are two different products for two different markets, and don’t compete. But that’s a cop-out. Both are mobile devices that Microsoft designed for mobile professionals.

So here’s the way we’re going to settle this once and for all. If you’re a corporate user, with a giant bucket of IT money sloshing dollars at perks like personal laser printers, oxygen bars and dry cleaning, buy the Book. It might be crazy-expensive, but what do you care?

But if you’re like us, just ordinary folks... well, the Surface Pro 4 might be more your style. You know how it works, you know what its limitations are, and if you believe in the Microsoft “rule of three” (that Microsoft never gets a product right until the third version), you’ll feel more assured that the Surface Pro 4 will be around for the long haul.

Honestly, though, we both feel the Surface Book and Surface Pro 4 are terrific pieces of hardware, and worth your money if you have it. You can’t go wrong buying either one.