Which is the best responsive theme for Wordpress

I am thinking to buy a responsive theme for my tech blog powered by Wordpress. I have been looking for days and am pretty much confused.

I like the theme of this site: http://www.labnol.org/

and this site http://blog.sudobits.com/

But I do not know what themes are those.

Can any one help me out by pointing me what themes are they? And also suggest some good responsive theme for a tech blog.