Facebook all the way.
In Costa Rica Hi5 is HUGE but FB is catching on.
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Way back around 5 years ago you'd have to have friendster account to be cool then they sucked so much and most of the users moved on to facebook. This is in the Philippines fyi.
facebook is king in my reigon (UK) Northamptonshire
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both are equally followed in different parts..they both are very good..
Facebook is universally very popular..