"Which Windows laptop should you buy?" That's no longer a tough question: these days, I almost always recommend a Dell XPS 13 or an HP Spectre x360. When these notebooks first hit shelves last year, they offered more style and performance than we'd ever seen for under £850.
In 2016, none of that has changed. The only difference is a new generation of Intel processors that are slightly faster. And I like it that way.
Update, November 2016: While this Spectre x360 is still on sale -- and this is the one I prefer! -- you should also check out my review of my review of HP's newer, slimmer model.
Starting at $999 (£849, AU$1,999), the 13-inch HP Spectre x360 has everything I need in a thin-and-light laptop. I don't ask for much: just a comfortable, lightweight machine with great looks, long battery life, plenty of speed and an excellent selection of ports.
I've been using the Spectre x360 for weeks now, and it ticks every one of those boxes. It's like an Apple MacBook Air with a slightly worse touchpad, but more connectivity and a far better screen -- one that bends over backwards to become a Windows 10 tablet in a pinch. Literally.
One big difference for 2016: there's a new 15-inch model that starts at $1,149. I tried both the 13- and 15-inch models, and they're practically identical. That's a very good thing. (From here on out, you can assume my notes apply to both models unless I specifically say otherwise.)
(In the UK, the 15-inch model is only available in a £1,299 config with a 4K-resolution screen. It doesn't seem to be available at all in Australia.)