Most obvious to the user is that there are no viruses that affect Macs. Not that it would be impossible to create one. It's just that nobody has. Under the hood, Mac OSX is BSD (a variant of Unix), which is considered one of--if not the most secure and stable operating system.
Now let's talk about where all the settings are stored. In every Unix operating system (including Mac, which is Unix, remember?), settings are stored in various text files (usually in the /etc/ directory). These text files are well documented, and settings can be changed with any text editor. In Windows, settings are stored in a database called the "Registry." The problem with this is that the Registry...
1) Has a finite size limitation unless you manually change it.
2) Gets fragmented, slowing down your computer.
3) Is cryptic, poorly documented, and difficult to edit.
4) When you uninstall software, it still leaves a bunch of junk in the Registry. This also can happen with those text files in Unix/Mac; however, with lots of text files, extra leftover settings aren't a big deal, but in the Registry--because it's a single database, this causes it to keep growing over time, which can severely affect performance.
5) If a text file with settings gets messed up, corrupted, or deleted, then you've only lost the settings for one application. If your Registry gets messed up, then you may not even be able to start Windows.
From beginning to end, the Apple experience is pleasant; from the excellent customer service at the Apple store to the superior engineering of the hardware and software, with lots of thought put into the little details. Case in point: The power supply port on Macbooks: It has a magnet that sucks the power supply right into it, making it easier and nicer to plug in the laptop. It's like the difference between driving a Nissan Sentra or a BMW. Either car will get you where you're going, but the BMW is just nicer.
Having said that, I've been a network administrator for 12 years. I've worked on Windows, Mac, more Linux distros than I can name, OpenBSD, FreeBSD, Minuet, ReactOS, BeOS, and more. As far as I have ever been able to tell, the only differences between Mac and Ubuntu Linux are these:
1) Mac has the Dock.
2) If you really want to PAY for commercial software, you can on a Mac, but on Ubuntu, you're limited to only free software.
I used all free software on my first OSX computer and then wondered why I had payed for a Mac when it wasn't doing anything that Ubuntu wouldn't do just as well or better. By better I mean that I had to use that weird AppFresh thingy to keep my Mac software up to date (and it didn't always work); however, Ubuntu keeps EVERYTHING up to date automatically. For $1,200 you can get an Alienware laptop that will run Ubuntu, and has better hardware than the $2,500 Macbook Pro 15".
Therefore my conclusion is this: If you're happy with all free software, then don't pay the Mac Tax; go with Ubuntu. You'll get all the security features of a Mac with Ubuntu as well. If you want to use commercial software, then go with Windows since it supports more commercial software than Mac anyway. In my opinion, there are only three circumstances where you *really* need Windows/commercial software:
1) If you're an avid gamer
2) If you're in a corporate environment where they have very specialized Windows-only programs. For example, I work for a court of law. The program that helps Judges to calculate alimony and child support in divorce cases is only available for Windows.
3) Video editing (which Mac is also good at, but not Linux)
For everything else, you'll find good free alternatives to what you're used to. http://www.openoffice.org for example is compatible with all versions of Microsoft Word, Excel, and Power Point, and it'll run on Windows, Mac, or Linux (or BSD or Solaris if you know what those are)
I'm a big Linux advocate since you can have the benefits of a Mac without paying the extra price for the Apple brand. Unfortunately, most people (incorrectly) think that Linux requires a bunch of computer knowledge, but they know that everyday Joe's can use a Mac. Because of that, and all of the above, it's easier to persuade folks to switch to Mac than to Linux.