This is a touchy subject for most. A lot of the production community is torn between using a Mac vs using a PC. Mention that either is the way to go on a forum and expect a flame war that will last for weeks.
Here is the truth; they are fundamentally the same. Macs and PCs have been the same for around a decade since Mac went intel for their machines. They are both based off the same kernel also, they share the same deep roots and all established developers of software support both.
The advantage of having a Mac is being able to use the proprietary software that it offers such as logic pro and final cut. Both are arguably the "standard" in professional fields. If you are into emulating trance guys and want to use logic pro go at it but the same producers will tell you it's bugged and crashes a lot when simply recording midi notes. (note that Avid is still used by most studios as aposed to final cut)
Using a Mac for editing film professionally was extremely frustrating personally, spinny wheel and unresponsiveness while scrubbing and encoding kinda turned me off for the most part. Using Vegas pro even on an older toshiba produced video that was comparable and did so in half the time (was still HD video in mov with h264)
I still have problems with my custom PC, I have to reformat every year to keep things running smoothly. Using ableton live 99% of the time makes it so I dont need a Mac. Also using high quality components and windows 7 makes it so it never hangs or freezes and since release of windows 7 it has never crashed(especially surprising due to my experiences with XP on the same hardware setup)
Logic on a Mac and ableton on a PC both run plug ins the same way, they both share the same 30 year old midi standard and they are both supported by hardware manufactures. Can someone listen to a track and tell it was mixed in logic or FL studio or ableton? What about ableton on a Mac? What about a Mac running bootcamp? Should we even go as far as to say that spreadsheets should only be edited on a Mac?
It comes down to price, components and software. With windows bases PCs obviously in the lead for price when you compare a Mac pro to something you can build youself. Components? Well the use the same components such and intel CPUs, Texas instruments chipsets and SATA drives. Software has already been mentioned as it does the same thing on both platforms if you exclude the proprietary software apple owns.
The final round; if you want a rock solid laptop go for the MacBooks. If you don't want logic and dig ableton build a PC yourself. There's no right or wrong choice here. The biggest misconception is that using logic will make your tracks sound better, they will sound the same but that rainbow circle will show up more.