this sounds more like personal preferences... great things have been done on all of the platforms.
that said though, i find macs much easier to use, backup, and maintain, for all things.blender
is a program you will want to try.
for games, you have to talk to the game developers... nothing really to do with osX,
since osX will run anything as long as the developers write the games to run on a mac.
actually though, you can buy a mac, and use apple's boot camp to install and run windows
natively on a mac, and play any game you like, since, with boot camp, you turned the mac
into a windows computer, just get a windows usb keyboard to use with it.
as with anything in life, the more RAM, the merrier, so get as much RAM as the mac will
hold, or as you can afford, 4 GB's would just be a starting point.
good luck with it