The chances are you'll get a load of emotional rants from both avid Windows supportes and fervent Mac fans, but there really isn't a lot in it these days. If you have a need to work with businesses other than the creative industry, you are probably a bit better of with Windows - but not much.
Windows machines tend to be cheaper to buy and maintain as there are thousands of manufacturers competing for your money, but if you are considering a laptop, this doesn't apply so much as they tend to contain lots of proprietory parts.
There are also lots more peeple writing software for Windows, which gives you more choice, but for the sort of use you describe, I would say it is entirely up to you - go for whichever you prefer.