We've three Macs around the place, one being a MacBook Pro I'm running Logic on. As the DAW PC expired recently I'm considering either new PC or putting Windows on a Mac using bootcamp. Or to fully switch to Logic despite it being annoying in a few ways. Not sure which way to go yet.
I like Macs, but I'm not an Apple fanboi any more than I am a Windows one, an IBM OS2 one, a MSDOS one or an AmigaOS one. I just happen to know and have experience of those operating systems.
Macs are far easier to configure for audio production than a Windows PC. Full stop, end of story. No issues with things like cpu sleep states, core parking, wifi drivers fouling up latency and all the other things that need attention to try and force Windows to behave itself. Apple's Core Audio and Core MIDI simply "just work". Using Wifi and bluetooth while recording at low latencies are no issue at all. Setting up a complex hardware-based MIDI setup so that every application will see it the same way, no problem.
Though the Windows configuration issues may come back if running Windows on Mac hardware, don't know because I've yet to try it.
El Capitan is very solid indeed. The initial update from Yosemite saw some audio hardware not working. Not because of Apple but because manufacturers, even including MOTU, didn't start working on a compatible driver until around or even after the OS release date. Despite months of warnings and pre-release versions of El Cap being available for months. :-/ The hardware people finally got their act together pretty quickly though. The driver issue seems to have largely been connected with Apple changing the USB driver to make it more standards-compliant and fix a minor bug or two.
OS X in general is a full-blown GNU/Unix system with a very good graphical interface. From a user point of view it does some things in a similar way to Windows, others quite differently. It seems to require less in the way of computer resources than Windows and generally behaves itself.
Updates are not mandatory, and disastrous ones very uncommon indeed. Apple know exactly what every Mac contains hardware-wise so there are far fewer compatability issues and unexpected consequences to updates. Using the Time Machine backup app you can image the entire system before updating then roll back if necessary. I've never had to roll back, but that's how to do it.
Things to watch in OS X/Macs.
There were many reports of fusion drives fouling up pro audio a year or three ago, though that seems to have been fixed. Personally I'd just go for an SSD every time, they work fine.
The lack of internal expansion means relying on USB3 or Thunderbolt external drives. Both are plenty fast enough, but the TRIM command cannot be applied to any drive using a USB interface, only Thunderbolt. Many USB+Thunderbolt drives won't accept it either. That's because of the USB/SATA interface. To activate TRIM on an external or non-Apple drive requires using the 'trimforce' terminal command (very simple).
Any hardware with 'Thunderbolt' in its name tends to be expensive. As do external drives marked "for use with Mac". So just get an ordinary 'Windows' one and reformat it.
OS X can read MS FAT and NTFS formated drives, but only write to FAT.
Time Machine is the backup app. If activated it scans hourly for new versions of files then does an incremental backup. Hourly is a pest if working with audio, and I'd rather hundreds of MB size audio files backed up by me copying them where and when I want to anyway. There's a third-party app available for getting Time Machine under control which works OK. Backups can also be automated by shell scripts if you're so inclined.
If you need to use the computer for other things besides a DAW, Apple's equivalent of MS Office is good and it's free. Photoshop etc. run as well if not better as they do on a more powerful PC. Games (and viruses) are the area where OS X is really lacking.
The biggest downside to Apple is the price. The hardware is seriously good quality, but you do pay for it. Though Mac users tend to upgrade (which means replace) their computers far less often than Windows users.
If I were buying a new desktop Mac for DAW work I would look at the iMacs that can be upgraded at purchase to i7 processors. Probably a 27" Retina model (Retina displays are fantastic). For less money, the 21" Retina. Laptop choice really comes down to which MacBook Pro you want to use. The Air is fine in it's way but not powerful enough to handle big projects and the MacBook, while powerful enough, has only one USB socket to talk to the world through. A 256GB internal drive is ample for OS and applications.
The Mac Pro is ridiculously expensive and looking a bit long in the tooth as well.
It's worth keeping an eye on Apple's website for factory reconditioned Macs. They're usually current production ones that get sent back from the Apple shops then thoroughly cleaned, checked over, parts replaced as required and sold at a 15% discount with the same warranty etc. as a brand new one.