I think it really depends upon your goals.
If you're building out a long term blog that you intend to use at some point in the future to monetize, then I would suggest you stay away from the free options, and get a simple hosting account and use Wordpress.org.
The cost is minimal - just $5 a month in shared hosting plus the cost of a single domain - but the advantages far outweigh the small investment.
The problem with the free route is that you really don't control your own site and over time, as your user base builds, that can become very limiting to your income potential for the site.
If, however, you're just doing it for fun or hobby and have no intention of ever monetizing it, then the free route is fine. Just keep in mind, many very good businesses "start out" as a hobby. Personally, I would never use the free blogs other than for "feeder" sites to my principal sites, but that's just because I'm more focused on long term flexibility.