I've used Apple for over ten tears, for one reason: digital audio workstation. Pro Tools is the world standard, and ten years ago, it only ran on Macs. A few years ago, they added Windows support but its always behind in features.
Its also very easy to have Macs for all my other computers (business, kids, nanny), but frustrating to overpay for less features and less available software. My 11-year-old daughter thinks every Mac is slow except for my Dual-processor 2.5GHz G5, and I kind of see her point. Still, Macs network together painlessly, and share printers, internet, etc.
I'm not loyal at all, but just taking the path of least resistance.