Good Ad Size

Wider ads are easier to read than longer ads.However, whatever size ad(s) you pick should compliment your website’s design.A wide ad that cuts into your content too much may be distracting.
A 160×600 skyscraper ad running down the left or right sidebar works also well when used in conjunction with other ads.
A decent advertisement size that is visible without taking away from the design of your page will have a greater affect on your ability to making money from Google AdSense.