The Ranger class is sort of like Aragorn from The Lord of the Rings. They're good at tracking and survival, at least in theory. The reason this class gets the lowest ranking is because it forces players to be kind of specific. Being able to have a favored enemy and
terrain is kind of cool because the character gets all sorts of bonuses, but if the Ranger is good, say, in the Underdark fighting aberrations, but the DM has set the adventure in a desert ruin somewhere, well, those bonuses won't do much good.
That being said, the Revised Ranger stats help balance this out a little bit. Players don't have to be as specific, but still. It might be a better choice to go with a Fighter class or a Druid class; something a bit more specialized.