Consolas is optimized for ClearType, which makes fonts clearer by not only using subpixel antialiasing but by also fitting them to the pixel grid.

If only I had ClearType on OSX, I wouldn't have to look at fuzzy text all day ( see this screenshot http://www.codinghorror.com/blog/2007/06/font-rendering-resp... )

Both Inconsolata and Consolas seem to look nice on Ubuntus default rendering (though Consolas only seems to look okay on a dark background).

I personally use Inconsolata.