Which has a greater design and features? And to think to the future, does anyone knows any statistic about which of these two has more success in Google ranking?
Neither does specifically well or badly in Google rankings. Where you rank will depend on your content and not on the framework you wrap the content in.
Blogspot is immediately related with Google, and can give you quick technical integrations with its products - by sharing the accounts.
Wordpress is feature rich.
http://pulsed.blogspot.com/2007/07/blogger-wordpress-chart.htmlIt has more detailed comparison except page ranking.
Probably no one has heard that google is biased to its related products.
As for features, Wordpress has the greater amount of extensibility and there's a lot more plug-in components available, so that might be the better one.