From your experience, do image ads OR text ads pay you more per click? From my experience.. image ads pay A LOT better than text ads on average!
It depends on the layout of the web page and the type of contents. From my experience, text ads fare better than image ads.
Image ads all the way, huge amount better. But then I find link units and search blocks perform well too.
I've always done better with text ads but that's because I lead my visitors into them in a very deliberate way, if you are just throwing ads up then image ads tend to work better.
I have to imagine that google would charge the maximum to an advertiser to take up an entire ad block? For example, with a 300x250 ad block, google can fit up to 4 text advertisers on it. But with an image, only one advertiser will fit. I have to believe there is a premium paid for this exclusiveness but then again I am only speculating. I think text based ads simply give the clicker more opportunity to find something in the ad worth clicking because of the multiple choice possibility that 1 of the 4 texts will appeal to someone. So, hypothetically speaking, it would seem to be reasonable to suspect that an image ad will pay more but have a lower chance of being clicked. But a text ad will pay less but have a greater chance of being clicked because of the choice of more than one ad on the block. Think about it, if you wanted to place a 300x250 ad block on a popular site, what would that cost you? Probably alot, google must realize this too. Of course, this is just speculation. I suppose you could conduct an analysis or find someone who already has. Basically change your ad block from text to pic, figure out the impressions, CTR, etc.. and calculate.
From my experience I always earn more when someone click on my text ads so I would prefer to use text ads most of the time
Generally I think text ads pay more, no point in worrying about it though. Using both images and text on a site will work well.