Okay, I have Mac OS X 10.4 and Ubuntu 7.Something lol (Feisty Fawn).
Mac is fab because...
~There are a lot of really good programs that are compatible with it, contrary to public belief
~My grandmother can use Mac, and I (a computer person lol) get confused on Ubuntu
~Mac is just fun and friendly and enjoyable to use
However, some bad things are...
~None that I can think of...
Linux is great because...
~It comes with the full suite of programs (OpenOffice, GIMP, etc.) already loaded ad ready to use
~It is extremely flexible and modifyable
~It is all open source (most of the time)
~It has all the features that Windows and Mac don't (Workspaces, etc.)
Some bad things, however, are...
~Installing programs onto it has proven to be a challenge for me lol
~The pre-installed backgrounds are ugly! =P
If I were stranded in the woods and could only have one operating system (lol), I would still definently go for Mac.
So, yeah, that's my opinion!