What is the best Google Adsense format?

What is the best Google Adsense format?

468 x 60 on most of my blogs. I am in the midst of getting rid of all
those large rectangles.

If you want to put banner type ads on your site you should pick the
468 x 60 banner with 2 ads in it. This type of banner can be used very
effectively on top of content or below it. The half banner only shows
1 ad and can be used everywhere on your site. Its size is 234 x 60
pixels. However if you want to go for a more vertical layout of your
ads the 120 x 240 pixels vertical banner may be the one you are
looking for.

DETAILS : http://perfect-adsense-tips.blogspot...se-format.html