Its simple, if you are using your own domain name for blogging or site. You must use Wordpress. Blogger is just great for free blogging. With WP you can avail thousands of handy wordpress plugins to tweak-out your site or blog. So, in my opinion both services are useful and professional in their own circumstances. Thanks !
If you're blogging about your business, I guess you should buy your own hosting and install the Wordpress.org platform. Wordpress works best for me.
If you go to free route - I suggest you use blogger.com. Unlike what many others said, wordpress.COM doesn't offer lots of flexibility. You can also custom domain your blogspot and make it yourname.com cheaper when you using blogger.com instead of wordpress.com But I strongly suggest that you use wordpress.ORG if you want to create business site. It offers great range of customization from its plugins repository.
Doesnt matter, if you write good, unique content. Comparing abilities as CMS wordpress is much more flexible.
I believe in Wordpress if you have your own hosting, Blogger is good also but if you have your own domain name, and own hosting go with wordpress, it's very easy to install and use. As far as good content no matter who you go with you always need good content to get ranked by the SEO.