Adsense is a great service as long as you don't get banned. I've never used chitika but I read the PPC is lower then adsense. I would advise that you don't click your ads maximum of 20 or so clicks per day.

I don't think Google would care if they are both the same font color.

I the most important factor are the earnings. With adsense you may earn much more than with any other advertising programs, just that you can get banned very easy.

both are same font colour that not a problem....many website sould use it....so don't worry

Chitika is a well-known PPC advertisement like Adsense. It straightforwardly competes to Google’s AdSense. Chitika allows you to have reasonably higher PPC value than Adsense. Chitika offer an image in advertisements, which can catch the attention of more visitors to click the advertisement.

Chitika is a data analytics company in the business of on-line advertising. Through the application of data and innovative technology in the fields of mobile, local and search Chitika has developed a vast global network that maximizes yield for both publishers and advertisers.
This is the information from its official site!