Text Link Ads VS Image Ads
There are two different kind of ads that you can use for your site, text link ads and image ads. There is much difference between the 2 even though both of them serve the same purpose, to deliver targeted traffic to a specified website.

Image Ads
Image Ads are usually very colorful, and they are usually animated. Image Ads are specially created because They attract the visitor’s eyes to the ads so they will be inclined to click on the ad.
The ads for an Image Ad can be made with any type of file extension, it doesn’t matter whether it’s a .jpg or a .png, it just has to load fast. The most commonly used type, and most recommended type of ad file extension are .gifs, they are used in almost every website that you visit for their good image properties and their fast loading.

Image Ads only appear one in an Ad block, so if you have a 468 x 60 ad on your site, only one image ad for one website will be shown, the Ad blocks are not shared.

Text Link Ads
Text link ads are faster loading, they are less colorful than Image Ads and they can come in a variety of different colors. You can choose the color of the ads by either changing your Ad code, or changing the settings that you have on your Ad Publisher’s account.

Most of the times Text link ads are shared with other people. It is very often that you see 3 or more ads from different websites in a 468 x 60 ad. Google now allows more ads on an ad block as they now have a script that allows you to change pages from the ads that you place on your site, so sometimes an Ad might has up to 6 Ads or even more.

Conclusion
It’s up to you to decide which ads will work best for your website. If you are not sure which ads might work best on your website, it’s recommended that you get both text link ads and image ads. Use a tracker on both of the ads and see which type of ads get the most clicks.

Furthermore, the only reason why I don’t use any Image ads is because Yahoo Publisher Network does not allow me to do so at the present time. I will have Image ads as soon as they allow me to have them. So just because I don’t use them does not mean you should not use them either.