I too would namedrop @Empire LRP in the UK - had the honour of playing one weekend last year and it was the best LARP experience of my 15+ year LARP career!

But my favorite LARP of all is the fake one we created for neverland: Amazon.com: Neverland: The LARP Sitcom: Kevin Adams Jr., Eric W. Espinosa, Chrisopher Michaels, Craig Ernest Woodward, Robert Paul Verdi