the ad size that fits most comfortably on your page is the best size to use. they will show the same ads, so concentrate on positionioning the right size in the right place.
If you can fit the larger sizes, go for those. Common sense tells me that if I show 4 ads on my page, there's a better chance of someone seeing something that attracts their attention than if I only have 2 ads, right?
Adsense question.
Linear Mode
