WordPress .org vs .com

Hi

I’m new to online marketing.

I strive to build a successful http://www.messyah.net, – should I use .com or .org?

The purpose of the blog is to build a community (and sell products like e-books)

And as a “partner” to the blog, I’m going to build a site http://www.20wisdom.com. Should That site use wordpress .com or .org?

Thanks.

– Jonas