Personally, I would recommend getting your own web domain name. If I come across a blog and it's "xxx.wordpress.com or xxx.blogspot.com" or any other blogging platform, I usually leave after a second. It may be a great blog for me to read, but if the author doesn't take the time to get there own domain name, it's hard for me to take it seriously.
Anyone and everyone seems to have a "xxx.wordpress.com or xxx.blogspot.com" blog, and I find most of it is useless. Please don't get me wrong, there are one or two blogs like that, that I read regularly. But if you do take that route, I wish you the best.