There are lots of reasons people prefer Macs, but on a basic level, PC's and Macs are the same thing... only different. They both have a screen, a keyboard, a bunch of circuitry including a CPU, video, storage and interfaces.
The differences are:
1. PC's cost less.
2. The OS's are different, and each requires software designed for the specific OS.
It gets down to two issues, money and commonality of applications among your friends and peers. For example, in high level professional film, video and music production, Macs have a large number of installed user bases. If what you'll be doing ever day is primarily Mac-centric, and you want to share files and basic user knowledge with the people with whom you'll be associating, get a Mac.
To put it another way, they're both tools. If someone wants to hire you to do a job that requires a phillips screwdriver, you can't insist on using a hammer.
That advantage is slowly disappearing because PC's have pretty much caught up with the performance and elegance of Macs, but some differences still remain.
As your dad says, the biggest advantage of PC's is that of volume. PC's are still well over 90% of the market which makes the hardware and software much less expensive and more widely available and servicable, and PC's can be built with much better CPU's and more RAM for far less money than you'd pay for any similarly equipped Mac. And that's before you get to the extra expense Apple imposes simply because they have a monopoly licensing position. That same balance is one reason there are more virus attacks on PC's because the bad guys want as many targets as possible.
If you really like the Mac OS better, one solution could be to buy a Mac and install Windows to run under it. Another would be to buy a PC known to be compatible for use as a "Hackintosh," that is, a PC where all the hardware is compatible with the Mac OS and hardware that accepts the required hack. Use the forum search engine to search for Hackintosh, and search the web for the same.