I bought a mac purely for two reasons:
1. Windows doesn't have Helvetica font, even if it does it the rendering is so terrible you cannot read it.
2. OS X Graphic User Interface is sleeker than Windows
1. What? The Windows font is just thinner and not an option unless you type it into the word processor. It still looks the same and it is not "rendered terribly". The windows PC is 1920x1080 and the Macbook Pro is 1440x900. 11pt Font in Pages for Mac and Word 2010 for Windows.
2. I agree OS X is more appealing and much more "modern feeling" however I like that Microsoft has stuck by their original design pretty well. It hasn't changed much for a really long time and that isn't really a bad thing.
I bought a Mac because I wanted a good, stable laptop that was portable, looked good, ran a good OS, and had applications I could take advantage of like Coda. I also wanted the option of exploring iOS development at some point. To me it was a matter of personal preference and I have plenty of Windows machines in the house so why on earth would I buy another? I don't NEED it.
I like Mac for browsing, school, and work related things. I also like having the ability to freely hop between OS X and Windows. I don't think either is "better" than the other but they are certainly better suited for different tasks.
My Windows machine is a 2600k @ 4.3Ghz, 8GB of RAM, and 2 overclocked GTX580s in SLI. It is plenty "snappy" for me in windows and I am well aware I can run OS X on a PC if I jump through hoops while standing on my head but it is much easier, and much more legal, to simply purchase a macbook pro for a couple hundred more than an equal quality laptop from the windows camp that can run OS X.