Lots of reasons. I’m pretty comfortable with my nerd cred (was programming graphics algorithms in C in high school) but buying a windows laptop was a Byzantine experience for me. I need a good screen, good battery life, and good keyboard/touchpad. There are Windows laptops that have one or more, but it’s hard to find one that has all four, and even if you do, there is no guarantee that the same model will have the same qualities on the next iteration.
Because they are so cost sensitive, Windows laptop makers build SKUs based on the hardware that’s available and cheap. So maybe you get a great display, but there was a good deal on crappy touchpads. Or you get a lottery where the same laptop can come with screens of widely varying quality (Toms hardware just did a piece about this with respect to Lenovo).
My Windows laptop purchase recently went like this. I was looking for a replacement for my 2012 MacBook Pro Retina 15”. Dell was out because of coil whine (which has been a problem with Dell machines since I owned an XPS 15 17 years ago). I stare at text all day so a high-DPI display is clutch. But almost every PC vendor make you choose between 4K and 5 hours of battery life, or HD and 10 hours. No well balanced 3K display with 8-10 hours like Apple has. (Again, this is because they’re stuck with what the hardware manufacturers are offering, they don’t have the clout and margins to demand custom panels.) Same thing with Lenovo’s 15” laptop options (they do have a 3K 15” display but it’s quite dim). HP didn’t have Precision touchpads. The Surface machines I’ve owned have been a Q&A disaster (it took them how long to get connected standby working?) And the 15” Surface Book is too much fiddily convertible tablet shit I’d never use. I ended up with an X1 Carbon, which was a bit of a compromise because I wanted a 15” screen. But it ticked the boxes of good screen (WQHD), good battery life, etc. It took a lot more than 30 minutes, and in the end I didn’t get exactly what I was looking for.
Even then it wasn’t sunshine and rainbows. Lenovo has awful quality control. I had to reinstall the Os to get rid of Lenovo crap-ware (and gained 2 hours of battery life in the process). I got a few dead pixels within 6 months. They replaced the screen, but now the bezel is peeling (it is just a fucking sticker, on a laptop that’s $1,500 even heavily discounted). The fibocom WWAN module has never worked properly (like requires a reboot every day after getting disconnected). So the one paper advantage over an apple machine is a dud. (And again, it’s because Lenovo sources parts from whatever is on sale that day—the Sierra modules that come on other iterations of the X1C are great.)