These jaw-dropping prices for long-haul F seats are impressive, but I don't think it really answers the question of what is the "most expensive route worldwide". It merely answers the question of "what is the most expensive seat worldwide?"

First of all, you can guess that over the course of a week, there are only a relative handful of people paying full F fares on those routes. Corporate bigwigs, celebs, etc. But on a 747, they would only represent a tiny fraction of overall seats. Many F seats would be upgrades or award tickets, and F only represents a small portion of available seats to begin with.

I think to truly answer the question (and this may not be possible), you would have to find which route is the most expensive when you average together the actual fares that are paid on the route over the course of say, a month.

A route where even advance-purchase economy seats are well over $1000 is probably going to be the winner. My guess is that the poster who mentioned the LHR-LAD route is on the right track. There are many obscure African destinations that see only a handful of inbound flights a week from Europe.