When my AdSense account was still valid, my conversion rates averaged about 18% in all my "made for AdSense" sites with red color titles. The blue color averaged about 12%. This was tested in two different months (blue first, and then red the next month). I didn't test this with Ad links though. The text and the url colors were light grey that is very hard to see.
Thanks for the tip. I've always went with the blue links. Going to give this a try. I have some sites that could really use a boost in ctr, might just be the niche though.
You are somewhat right about the niche. I had sites on nail polish and eyeshadow, and they were terrible in conversion no matter which color I chose.