I think you can`t really name a best trip report. There are so many really good reports - and also so many different styles here on flyertalk.

If you want to learn about what to expect on board i really enjoy the reports by SFO777 - for example this report:
http://www.flyertalk.com/forum/trip-...rg-munich.html
the best available description of Lufthansa new F anywhere on the web (including everything the airline itself provides)

If you want to learn something about your next destination - just look for a tripreport of UA_Flyer and his faboulus pictures. Let`s be honest - everybody can take a nice pictures of sights like the Sydney Opera House - but his pictures of everyday streetlife around the world are simply amazing.

And finally - if you want to learn what to avoid or not to do while on the road (or simply want a good laugh) you can always read one of eightblack`s "adventures"