This week google launched their feature to change the font-size of ad content blocks. But my question now is, what font size are you using right now. And maybe, more important do you see any influence on your CTR/Earnings? I have changed it to "normal" and actually my earnings dropped significantly (although it can just be some kind of fluctuation). But I certainly want to know what your first impressions are
I have not used that feature yet, too lazy i guess but it will be good to use the same font as your other site content. in my case it should be 10. i already used the font face option, "verdana" when adsense gave that feature, but i did not find any difference in the ctr/earnings.
I have changed the font size to medium and I saw some increase in CTR. Then i changed the font size to large and that decreased the CTR. So at the moment, I am just experimenting. I have again changed the font size to medium to see if CTR increases again or not.
I would use one that blends into my own sites fonts. Make it look like the links are a part of my site.
I tested all sizes for several days. Finally, medium size Verdana increased my CTR and earnings significantly (almost doubled)