Warrior's seem to get more of everything defensively, mitigation tables aside. Even double attack is higher than a Rangers. I don't see much of anything the Ranger excels at over a Warrior, but for leveling purposes the snap-agro class always wins. I seriously may try Ranger tanking. I think it will bother me not taking this opportunity to know.
I really think that if someone ever wanted to start a Ranger, NOW is the time at Green's launch!