I want to know what are the best colors for text adsense ads and what are the best sizes for adsense ads ?
You will never ever get an answer for that which will work on all pages. You need to figure these things out yourself as most people will not tell you what works because they've spent a lot of time figuring it out themselves. Overall, I would suggest that you start conducting your own split-tests to determine which works best for your site and ultimately your visitors
Make the TITLES/LINKS the same color as the text links on your site. Also, make the TEXT description the same color as the text content on your site. The URL...up to you, but I prefer a lighter gray color. Size? There is no best. The 'best' for me may not be the 'best' for you. Experiment. The goal is to make the site not look too 'spammy'. I run a linkunit at the top, 250x250 halfway down amongst the content, then a leaderboard at bottom. EDIT: For font size, I use the 'small' Verdana option. It looks best on my site because the font of my content is small Verdana anyway, around 11px.
I think it's best that it varies with the theme color of your website so that the readers and subscriber would think they're included with you web contents or assume that your website offer those ads formally.
Blend the ads with your content color. It will look as a link instead as an ad and the CTR will aslo increase.
the color has higher hue than your page, brighter, highlight, darker.... the best font is verdana the best size the largest