The best datingsites are different from country to country. But some date sites are bigger than others. This graph pictures the evolution of visits of major online datingservices:
Source: http://www.google.com/trends?q=meetic%2C+match%2C+freenet%2C+plentyoffish
The number of visitors of these dating sites are very different from country to country. Meetic is the absolute number one dating site in La douce France. Freenet is the number one in Germany. And Plentyoffish is huge most of all in the US. This graph demonstrates that worldwide, the american-based dating service Match.com has the lead. As this graph measures the search volume for a particular keyword, it could be that the search for "match" (as in "tennis match") adds up to the frequency.
Meetic grew fast until 2007, with lots of female members, had the most visits in january 2007 but has been declining since, probably due to the rise of Facebook use. The Germany-based datingsite Freenet is quite steady, with a small decline over recent years. Plentyoffish, run by one single man, has been growing until 2009.
Would it be that Facebook is taking away visitors from these classic dating sites? Let's have a look at the impressive growth of FB:
Source: http://www.google.com/trends?q=facebook&ctab=0&geo=all&date=all&sort=0
Well, there might indeed be a impact of the exponential growth of facebook.com in 2008, because its quite natural to look for a date amongst your Facebook-friends, and online dating such as Zoosk brings the Facebook singles together. This seems in relation with the relative decline of traditional dating sites, such as Meetic and Freenet.de. On the other hand, Match seems to be indifferent to the FB-ascent.