No one say the best text color for your site without knowing color scheme of your site. But you should know that text color of your ads is very important to make them click. Because visitors should exactly focus on the ad to click ads. One important factor of your ads is text color. According to the bellow figure highest CRT is represent color code of "000001" it is 7.16 % but you should adjust post background color, ads link color, ads background color also to reach that much of CRT.    

Bottom Line: Stick to the blacks with your text color.