Never heard of blog.com
Blogger.com on the other hand is probably the biggest free blogging platform available. Using blogger.com is just about fool-proof, and in my opinion should be made a compulsory experience for anyone starting out online. Because it is so very user-friendly, you can concentrate on your content and marketing.
There are limitations to any free service, and it would be wise to accept that you will eventually be moving your online endeavors to your own self-hosted website. For that reason plan your online presence, using whichever free platform you eventually choose, so that there is a natural progression toward your ultimate goal.