Best website to leave a REVIEW?

Which website is the best place to ask a client to leave a review for my listed business at? There’s Yelp, Google Places, CitySearch, etc. Which one would carry over to more review sites? I don’t want to request a review on Google Places, and then have it not get culled by other review sites. In other words, I want the same review to appear on multiple review sites. And I want it done automatically via SE aggregators. Which is the best strategy here? I would be greatly obliged for an expert’s opinion.