I'm a musician and occasional composer, and a Windows PC user. I've heard a lot of times about benefits of using a Mac for these purposes. But I wonder: what are these "benefits"?
This has been a raging debate for the past 30 years or so. There has been a healthy competition between the two platforms in an effort to corner a large segment of the market share.
In the beginning, Macs targeted the creative artsy types and the platform had features and benefits specifically geared to favor musicians and photographers and graphic artist. It was not just the hardware that favored the artsy users. For many years it seemed that most of the software geared towards serious professional music production was developed for the Mac OS. Many who were indoctrinated in the beginning, are still very brand loyal today and continue to spread the mantra that Mac is better for music production.
But nowadays, the PC has evolved and caught up with the Mac in terms of both hardware and available software. There are a few proprietary programs that will only run on a Mac, but there are competing programs for PC that pretty much do the same thing.
So capability and software availability are no longer the primary consideration when trying to choose.
In the old days, there were some compelling arguments favoring a Mac for music production. Today, the distinction is not so significant. It really boils down to personal preference and which platform you are more comfortable with. If there is a program that you want to use that only works on one platform, that could also be a deciding factor.
One thing that no one has mentioned yet (I think) is the audio driver.
On Windows, to get multiple audio drivers you either need to use the windows driver, which in general doesn't work very well with DAWs, has more latency and limited multi-device options, or use ASIO4ALL which allows you to combine the inputs into one device and work with low-latency, at the cost of sporadic stability issues and hardware incompatibilites
OSX on the other hand comes straight out of the box with "Aggregate Device" driver which allows you to easily combine multiple devices into one that can be fed to your DAW. Hardware producers also have a much easier job targetting a very limited Mac spectrum, which in general seems to make it all more stable.
This still depends on your choice of hardware, though, so don't make a decision based just on that. There are people who had success working on Windows with multiple devices just fine, and there are cases where a device refused to work with the Aggregate Device driver on OSX as well (one case I remember was when the producer didn't choose to support it because it would mean a drop in quality IIRC).
Another thing that comes to mind is that a lot of vendors see the potential in the Thunderbolt interface. Given how scarce it is in non-Apple devices, getting one might be your only choice for using some of the hardware as well.
The only difference between using a Mac versus a Windows computer is that with a Mac you can run Apple OS X which is required for a very few pieces of software that some musicians really like, and Windows is required for a few other packages and Windows is more affordable when purchased with a Windows computer. Particularly, I would say Apple Logic Pro and Apple Mainstage are very nice products (although they are not very intuitive to use) and are of course OS X only. Cakewalk Sonar and FL Studio are major audio workstation packages that are only available for Windows. You can use BootCamp to boot a Mac computer into Windows in order to run Windows-only programs on a Mac, but the extra cost to buy Windows to add to a Mac (Windows 10 Retail is USD 120 at this time) is a noticable difference. You cannot boot a Windows computer into OS X. So with a Mac you have the possibility of running any software package (for a price), while with a Windows PC you will not be able to run any OS X-only software.
The hardware possibilities are pretty much identical, so it's only the operating system that is the essential difference between the two right now.
In the past I have worked on the exact same project on both a Mac (in the studio) and a Windows computer (at home) and found no noticable difference in the process that was related to the computer in question. I've also started a project on a home Windows computer and finished it on a home Mac computer.
One could argue that there are advantages to the Core Audio API and the Audio Units plug-in format (both Mac/OS X specific and not available on Windows), particularly compared to VST (which is platform independent). This forum thread seems to indicate that plugins which are available only as VST and AU formats might work better in AU format, which means you would have to use them on a Mac to get the "better" version. Personally I have not really noticed the AU version of a plug-in working better than the VST version of the same plugin. As far as I know, the Apple plug-ins are the only ones that are only available in AU format (and therefore require a Mac to use them).
The reason why I personally buy and use Apple computers is that I prefer the quality of Apple displays and for some reason it doesn't seem like anyone else makes a display that I like as much. I do also like Logic Pro X, especially for the price, but I use Reaper more often and that is available on Windows also. My favorite software remains ProTools which is available for both and has its own plug-in formats, but I currently do not use ProTools because it has not been affordable for me in recent years.
Well, it depends what tools you need when composing music on a computer. For me - as I often make compositions for projects on a tight budget - I like to have a large set of virtual instruments. After 10 years of using Cubase on Windows, I switched to Logic on Mac. A switch I never regretted since!
With Logic you pay 500€ for 40Gb of instruments and audio effects. Add to that 2000€ for a performant Mac computer, and you're well set for 2500€. On the other hand with Cubase you'll easily loose 2000€ on a decent VST instrument; and then we're talking about a few instruments only.
This was something like 10 years ago, prices has changed a bit but the overal idea remains: on Mac platforms you pay for hardware and on Windows platforms you pay for software. And I have to admit I became a Mac fan since, for its sleek user-friendliness.