IBM published some interesting stats of MS vs Apple:
http://www.cio.com/article/3133945/hardware/ibm-says-macs-save-up-to-543-per-user.html
Personally, I've used MS based PCs for most of my life and switched a few years ago when my coworkers at a new job were using Apple based machines. Being a programmer, I really like the Unix environment in general and was always disappointed by the approximations that were available for Windows.
Working on a Mac feels like owning a high-end sports car, things are already installed or easy to install and just work in general. On a Windows machine, I've had to constantly look for the equivalent programming tools, download, manually install and then read the caveats of features that worked on Unix but not on Windows.
One my biggest complaints were the spaces embedded in filename paths. On windows, you ran into this "feature" everywhere whereas on MacOS, while available is much less common. On Windows the "C:\Program FIles" and "C:\Documents and Settings" would constantly ruin my scripting attempts as I had to constantly program around these directories whereas on Unix I could create a link as an alternative to the name and things would work.
My other complaint was the MS Windows switch to using a registry vs config files. This made is much more difficult to find and change settings using scripts. Navigating the registry was a whole other problem, with many duplicates stored making it difficult to understand how the keys and values fit together for a given application.
Apple is not without its problems though. Apple doesn't use the defacto Unix standards to store things in the filesystem. While they do have the standard /bin, /usr/bin, /etc directory for common unix commands, libraries and config files, they don't always store add-ons in the same places. The most notable is Java which gets installed in a very funky way in the /Applications directory. Why they decided to install it the way they did is a complete mystery to me. The only reason I can think of is Apple being Apple and its need to be different and difficult.
I've also used Linux a lot and it too is an evolution from the original ATT and Berkeley Unices with many directory sttucture differences and command name changes which took some getting used to.
My suggestion is to try them all and see which ones you like. Check out what your fellow students or coworkers are using and follow the trends they set. This will provide you with a good resource for overcoming problems you run into and in the coworker setting you will fit in better using common tools tools on a common platform.
As an example of problems encountered, try editing a document using MS word, Open Office on Windows, MacOS and Linux. You are guaranteed to have a broken document in ways you just can't fix after a few iterations of edits. This often comes up as you develop a software design document across team members using different word processors and/or OSes while allowing team members to comment on and edit portions of the document.