Create blogs in your own site will get your reputation up depending on the quality of your posts. Any internal links, which means hyperlinks going to your own domain, will not count in
SEO. Only those links coming outside your domain is counted. So for
SEO wise it is better to put your blog posts outside your domain. But do not neglect to place good quality articles in your own domain too!
You must maintain a good balance in your posts both inside and outside the domain.