Blogging on free domains vs. buying your own domain name

So after looking at a couple of blogs for sale in the other section on dp I got to thinking I might try my hand at spamming the internats with my own blogs and then try to monetize them with adsense. It also got me thinking, what is a better platform to blog from, paid or free? With wormyrant.blogspot.com I won't pay the tiny domain registration fee of $10 or so and get a free spot ready to blog but can I monetize it just as well as I would be able to monetize my own domain of wormyrant.com? How about SEO and visibility. Do blogspot blogs start out with a little advantage there in exposure? And regarding adsense revenue...does blogspot take a cut of your ad revenue? I see a lot of professional bloggers with their own domains but I see quite a few under worpdress.com and blogspot.com as well so just wondered, what are the pros and cons of each for people who want to blog for profit?

its always better to blog in your own domain rather than sub-domain because you will have ur own identity and freedom and don't have to depend on some other sites hosting and hence losing your identity.

Blogging with your own domain shows professionalism and that you're going to be there for the long term. When you buy something and put time into working on it, you can be sure that you're going to work and work and make something a lot better. These pertains to real life and online life.