There has long been a debate about the best OS out there, for sometimes frivolous reasons: PC is better than Mac because you can play games. Mac is better than PC cause it has faster boot up time. One thing is certain, which OS you use doesn't matter to anyone else, but you.
When I first started using a computer, as I'm sure most people around my age or younger, we all had Windows. Windows is nice, mostly because almost everyone has it and pretty much everyone has support for it, even Apple :).
After a while, though, I started to get a lot of small issues that would pop up. For anyone who started using Windows pre-Windows XP, it's quite common that after some time you would have to do a complete reinstall of your system, from scratch, after some time. This was due to the way that programs would, when you installed them, attach to certain hooks in your system. A common example of this is update managers. A lot of these hooked into when you restart your computer, it would immediately connect to see if there was an update. Now, imagine if you had 5 programs that did this, and each one had to pull in an update; that would take a lot of resources such as internet connection, writing to your hard disk, reading from hard disk, and maybe some CPU operations, let alone, some RAM to actually run the updater itself.
This is not to say other systems also don't have issues in themselves. As an avid Mac user, I've had some annoying issues that pop up once in a while, but I haven't had to reinstall my system from scratch, although I know a few other who did for various reasons.
There is one operating system which doesn't always get talked about which is Linux. Linux has kind of an interesting background if you ever want to delve in to it, which I will not want to get on this topic. Many people tend to dismiss it because of it initially didn't support of many popular games. This has changed quite a bit with companies like Steam supporting Linux which caused a recent resurgence in people using Linux.
All in all, people tend to pick a specific operating system and say it's better than another. When, in reality, you should pick what you're comfortable with and pick with what platform you will be deploying to/writing for. For people who will deploy to a Linux server, it's best to work with a *nix-based system, which is Linux/Mac, preferably use the same operating system so you can see how to setup and what deployment will be like. If you are developing a Windows program, then of course it makes sense to develop on a Windows machine. Don't get caught in a flame war, just pick what you know and preferably what you you will deploy to and just code!