Hands down for me the one licensed setting that I have no difficulty with in running games of. Star Wars WEG or FFG system. I love the flavor of Star Wars and I think that is just part of why I run such a constantly successful  Star Wars setting based games. I honestly thing that FFG and WEG both put a development crew together with the intent of making not only a good RPG but a Labor of love.
Another reason why I call to Star Wars over Buffy, Supernatural, Smallville or Dr Who. Each of these shows focused very narrowly on  a small group. It becomes harder to see the flavor of the world around them when the story is so very tightly intertwined with the main Stars.
Star Wars like these shows has a main cast with some depth to them.. But they are always in and around or interacting with a much larger entity be it Empire or Rebellion. Add in Bounty hunters and smugglers with their own Spice mines and you end up with a constant glimpse at a world around the main cast that is very active.. This for me made at least makes it very easy to imagine other heroes in the galaxy doing much the same as our stars.
Roll back into the Era of the Clone wars and there is just as much to pick from with Hundreds of Jedi running around the Galaxy now you have so much potential for epic story’s just be default in Star Wars. Add a dash of Madalorian Spice and you have a very Tasty story just begging to be told.
So there you have it my reason why in a quick nut shell I think Star Wars is one if not the best Licences RPG product out there.
Let me know what Other products you think do a great job with theirliscense out there