To find out what works for YOUR website put text adverts up for a month, the next month take them down and put up image adverts. After 2 months look at your stats and see what brought more clicks and use that.
it really depends on your website, some works better with text, some better with images and some works better witth images+text. you gotta try them out before you know it
I get most of my hits from text and it has a higher CPC for me but I run a combination of the two for variety.
I think images ads are better then text ads. if person upload a attractive banner on Google adword compaign.
both are good, it depend which kind of website you have. But my personal opinion is text adds are better
it depends on your website type, if its a games/movies website so it will be better to use images ads while if you have article based site then text ads are better.
Text is best for google adsense . But you can also use image depending on your website . For more information about adsense you can read How You Can Really Make Money With Adsense