The Mac vs PC debate is something that people seem to love to exaggerate. The picture that started this thread is an excellent example of this concept, and a lot of the discussion afterwards furthers it.
I am a mac person. My parents had owned macs there entire life and had made the decision to only own macs in the household. Therefore its what i grew up on and the system that I knew the best. As I went through my teen years I used windows on and off, and was more turned off by windows because it was a system I was unfamiliar with. I feel that this was the case for many people in the early half of the 2000's when confronted with the shiny new osx. Then I went to college and I had to use windows more frequently because of the "windows only" applications in the engineering department. This changed the way I thought about the mac/windows comparison. From my personal experience, along with the experiences that i have collected from my peers I think I can create a more accurate comparison.
Windows is a supercar, but not just any supercar. It can go the absolute fastest compared to any other car. Its panels can be replaced and reformed into an almost infinite amount of shapes, depending on the taste of the driver. However fairly frequently you will have to take it to the shop in order to fix something that, if not fixed, will prevent your car from running. If you are a talented mechanic, you could fix your car yourself but after numerous breakdowns you become frustrated with its poor reliability. In the end the vast majority of drivers will give up and buy another car.
The mac is a luxury vehicle. It goes fast, but not ridiculously fast. It easily overtakes the "econoboxes" on the highway, but can't keep up with the supercars. You can customize your vehicle, but only with certain options that are deemed fit for your model by the manufacturer. It only rarely needs to be taken into the shop in order to fix a catastrophic problem. It runs reliably and drivers are pleased with their experience.
The bottom line is that they are both cars, and they are both good cars. Windows is at times woefully unreliable. I can not tell you how many times I have had friends come to me with their 400 dollar dell laptop and say that they have done x process a dozen times, then took it to a store and got it "fixed", and yet it still is broken. They end up simply buying another 400 dollar laptop and pray to have a better experience. Not including the devices my family has owned, I have owned 2 apple products in my life. One 17" first gen MacBook Pro and the 27" i7 iMac I'm typing on now. If my memory serves me my MBP is 4 years and change old. I would consistently run it 24/7 under moderate load for various creative projects that I have pursued over the years. The only problem I have ever had with it was my battery died and needed to be replaced (for free from the apple store). My iMac which I bought right when the i7's were announced has just celebrated its first birthday and came with a defective speaker out of the box. After that was fixed I have yet to have an issue with it. It just cannot be argued that Macs are generally more reliable then PC's.
However Apple hasn't rode into town on a shining horse, ready to slay PC users left and right. The restraints on OSX as a whole are sometimes very frustrating. Things as simple as mouse acceleration are very difficult to turn off. Their designs are beautiful, but are limited. It would be like Richard Hammond's Porsche dealership. "Here is your 911, which color would you like?". Software support is sometimes nonexistent. Apple does a tremendous job supporting their own programs, including the iLife suite among others, but lags far behind on supporting any type of third party devices. I can't tell you how long I've been waiting for driver updates to help optimize starcraft 2. Believe me, I remember the 90's with OS8 and the only option for games being the oregon trail; it wasn't pretty.
I hope this can better explain the differences, and the advantages of the two OS's.