You can do both at the same time. Creating quality content and updating your website is very important task to generate some authority of you blog.
Web 2.0 is very easy to use and it can give you dofollow links. Mainly you can post on wordpress, weebly and wix platforms
Hi, Posting a blog at your website and sharing that link on web 2.0 sites would generate quality traffic. Both are the important things as you can not skip or choose one between two.
Whether you update content on Web 2.0 Or Target Websites, The Only thing you need to worry about is your content. If you publish eye-catchy content on boring blogs, still you will get benefit of it.
Update you blog with quality content regularly. From your post you can use that to link in your web 2.0 sites. Although I already gave up on the web 2.0 strategy and gave more focus to guest posting.