A few weeks ago I bought a Dell XPS15 (9530) from the Dell outlet. I'd wanted a machine that would have a life of around 5 years of decent performance, and was looking at a reasonably fast i7 quad core processor, 16Gb RAM and good graphics capability. A nice screen was also desirable, along with low weight, mac-style trackpad, good connectivity and a decent build, and this fit the bill well at about £1000 + extended warranty.
I'm operating-system agnostic, happy to use Windows, OSX & Linux and had previously owned a Macbook (late Dec 2008) that had behaved just like any other PC, including iffy hardware, and become frustratingly slow despite upgrades etc. I'd looked at the possibility of another Mac, but anything with a decent spec was quite expensive, even as a refurb, and worst of all, retina Macbooks can't be user-upgraded.
So I bought the Dell.
The place where Apple have really won is in the way they present a new computer to you: defaults are mostly logical, and when you first boot the experience tries to win you over with animations and exciting discoveries (this wear thin after a few weeks, when the machine indicates you're too stupid to be allowed control). My windows 8 experience was the opposite, with default settings being generally illogical, badly chosen or just irritating, but as I adjusted the system it eventually became smart, clean and flexible. TBH there's little to choose between them in practice - both will continually send you updates (sometimes large, sometimes they'll break your machine). If they will run the software you want fast enough then it doesn't matter really. The one other key difference is that windows manages workflow for everything through the task bar, but OSX relies on individual applications to manage workflow, and if you have a lot of - say - text documents and spreadsheets open at the same time then it can be really tricky navigating through - though they have addressed this somewhat in the last couple of OS version.
So I'd say use what you like, but you can get a great machine for significantly less than a Mac. Check out Chillblast as well as Dell.