Why a Mac ?
well, all of the good sensible reasons above ....
And yes , actually also because they are a very nice bit of kit . I do enjoy them.

I use a new iMac at work for the graphics/design work I do and have an assortment of iBooks, a Powerbook and a MacBook at home that I and my family use .  For 1 month my teenage son borrowed a pc laptop off a friend as he thought it might be easier as all his in-school work was done on a PC .  I ended up doing all the maintenance on it for that month ... complete with two bad virus attacks, multiple crashes and having to do full system re-installs...   a total nightmare timewaster .  Never again ! 
I spent more time messing with that one piece of equipment in a month than I do on all of my other Mac  computers put together in a year .

" Try and be nice to people, avoid eating fat, read a good book every now and then, get some walking in, and try and live together in peace and harmony with people of all creeds and nations."
-Monty Python