Hi,

I want to know which ads format is the best for earning, image ad or text ad or link unit, which is the generate more money

Thanks & Regards

I think it depends on where on your site you are inserting the ad's , and which type unit blends in and works best for that particular ad spot. so usually a mixing of the offered formats can work best.

My experience

Text ads - 336x280 surrounded with text content(color of the ad should be the same as the text color of the content).

I was just reading the guest post by problogger on the official adsense blog in which the author of problogger.net says that ads with image and text ads enabled work out better than just text ads or image ads.
But then, he also admits that the best way to test your success with adsense is by 'experimenting'