The best FP in the game

It is the one from Dalaran to River's Heart in Sholazar Basin. No, not because it finally crosses over Wintergrasp or because it's a good farming zone. You're thinking of the wrong flight.

I mean the one that gets shot down, leaving you to run the rest of the way. That's how flights should work: they save you some time but they're not a trivial ride, skipping over everything in between.