My stats show higher clickthrus with overture - if you're in the top three advertisers - as these are the first listings you read as you scroll down, and in some cases only these three are carried. But my google's adwords at the right of the listings are also getting good clicks. Surfers can tell immediately on google that they are ads, whereas overture's look similar to normal listings.
If your campaign can afford it, go for both for maximum saturation.
If your campaign can afford it, go for both for maximum saturation.