My 2 cents:
Switched to Macs at the office, home office and laptop (15" retina MBP) about 5 years ago & there's no going back. There's a major reason that people interested in scientific computing prefer the Macs: OSX is a modern GUI built on top of a UNIX foundation, so you can do all your low-level shell work natively. These are the best machines I've every owned. So smooth, fast, intuitive, powerful. The engineering details in the fit and finish are amazing too ... absolute things of beauty. Had to upgrade my wife's computer recently, and went for a low-end Toshiba for budgetary reasons. She doesn't live on the computer like I do, and we couldn't justify a Mac. I spent most of a day just getting the adware and junk off of it. The screen is horrible -- especially off axis. The design is clunky. And having to use Windows for any amount of time drives me through the roof. The apple approach is so much more elegant, minimalistic, refined, unified, cohesive, functional ... software and hardware both. The prices are higher, but the value is there, no doubt. Pricing a Dell (for example) with comparable processors, memory, screen, and form factor is not going to save much money after all the upgrades from base configuration. Finally, I've never found the software issue to be problematic. Everything I need pretty much is available for OSX, and there's quite a bit more usable free software pre-installed, for that matter.
All, just in my opinion, of course
Funny story: I was at a high performance grid computing conference a couple of years ago in Indianapolis. During/between presentations the house/podium computer crashes. I say to the guy next to me "Is there a computer expert in the house". He says "Yes, but its probably Windows -- No one here would know what to do".
