Rule #1 for Seo, don't rely on a web builder program to create your website. Either it will give an excess of troublesome code or not give enough code.
If you don't know anything about web design and expecting to get a high ranking Seo site in the search engines then go with a wordpress blog setup and make sure there is a sitemap, robot txt, and meta tags linked to it.
Another great cms is drupal, a bit difficult to grasp in the beginning but if setup properly can be an seo powerhouse. Don't forget download size, google started calculating this into their algorithm so make sure the site is optimized correctly for visitors and search engines.