Foursquare, Gowalla or Yelp?

I attempted to maintain Foursquare and Gowalla at one point but when Yelp had check-ins, I made a choice to stick with Foursquare. Reason being: Foursquare has gone international and it's ability to detect your location is not as sensitive as Gowalla. Sometimes, I would be in the building and for some reason, I wouldn't be able to check in with Gowalla. Whereas, Foursquare, you can be uber far away and still check in. Thoughts?