My thief and guardian are going to be Asura. Everyone thief and their mom will be a human with a bit of spill over to the other races. I had a Norn thief for the BWEs, was too big. Looked weird towering over everyone while trying to stab them with daggers. Asura thieves look like small packages of terror. Their animations are also very acrobatic. The guardian is to be ironic. Most guardians will be Norn, I'm making the smallest guardian toughness specced guardian possible. Funny because I always said I would never make an Asura.
My Mesmer will be Norn because shamanism. The Mesmer is the most "mystic" of the magic classes with its illusions and stuff. Norn's are shamans who can shapeshift. Shapeshifting will be part of my Mesmers back of tricks.
My last character will be an elementalist human. Because I can. I don't plan on making a Charr of salad person.
Humans because I happen to be a member of their species, unfortunately they'll be destroyed after the dragons are gone so it feels like your saving the world for the Charr and Asura.