I assume you mean a CMS (content management system) when you say website. Or do you mean having your own domain verses a blog at blogspot?
Which ever it is, I would suggest getting your own domain and hosting, that way you control the content and always have acess to your stuff. I pay less than $60 a year for my hosting which provides me 1GB storage, 20 GB bandwidth,email accounts, mysql DB, and a bunch of other stuff that allows me do run my own free copies of CMS, forums, blogs, ....... WITHOUT ADS...
When you own it yourself, you don't have to worry about corporate buyouts or policy changes that put all your previous hard work in creating content in jeopardy. If your hosting changes policies/cost, or goes belly-up, you just take your stuff to another hosting firm. The possiblilities are pretty much unlimited with all the free software packages out there. We are currently working on adding member blogs to this site as we continue to expand the member experience and value.
Oops I just let the cat out of the bag! Stay tuned.
It's also nice to have your own email. Something like email@example.com
is much nicer that firstname.lastname@example.org