
GreyWolfLord |

Some of those I didn't think had any 3e/3.5/PF support (planescape or Lankhmar for example) except maybe a one off or something article in Dragon? Ah, saw your second post.
I think Dark Sun was actually covered in one or two dragon articles.
Though, my to ones probably if you include PF would be
1. Forgotten Realms
2. Dragonlance
3. Golarion (but which one, that's more unique)...which would boil down to...(a) Five Mountains/Darkmoon Vale (b) Sand Point/RotRL/CotCT/SS (c) Ustalav
4. Star Wars Saga Edition(if you can count it)
5. GreyHawk