related colors blend the ad in, makes it more likely to get clicked, i've had success with that than the default colors
Related colour make a bit more income for me since it was blended and people will think it's part of the site not an ads.
Default colors give the visitors the impression that they are navigating away from your website or blog. I've had very good results from blending my ads to match the background color.
I start with blended ads but I always try out different palettes. Always good to experiment. I have been surprised in the past!
Blending the ads so that they dont stand out is the wrong way to do it. Dont have borders but have the url colour bright green and have the title text a default blue. Change the link colours of your site if you want, but dont change the adsense link colours. Works best for me
I just experimented the last few days with making my ads stand out (my regular links are black and my ads are blue). My CTR went up.