My Wife wanted a blogging site to try, so I had the choice of setting up my own server or signing up to an online provider.
I first looked at setting it myself, and after doing the sums, I calculated it was going to cost me roughly $10/month in electricity to run a computer to host it, all the time to maintain it, the learning curve to set it up and the pain of trying to work behind a public IP address that changes every couple of days.
This compared to $6/month for hosting with Bluehost, which specializes in hosting blogs with WordPress, so it was a no-brainer. I would host it myself.