Still has windows 10 on it (my only windows machine) since I need occasionally to use the latest versions of office, and I use eclipse for the odd bit of programming I need to do away from my main dev machine (common workspace with linux is awesome).
Macbook Air was good, in 2008. couple of the staff use them.
Be aware, unlike the Macs the different versions of the XPS13 over the years are very different machines. Only this years model has the 14 hour battery life for example. But many stores (such as Amazon) stock old models.
I was actually commenting to collegues last week that Dell appear to have become the world leader in "real" computing - laptop, desktop and server. They have a lot of skeletons to shake though before they are perceived that way.