The Ranger has been very well overhauled in my opinion. I was actually in the process of remaking Ranger when I discovered Paizo had beat me to it. I have no complaints - save two.
The Rangers favored enemies are a grab bag of both good and bad choices. No ranger goes without taking Evil outsider, but I've never seen one take animal as a favored enemy. It is simply not worth it. I have a few suggestions.
1. Animal and vermin favored enemies should be combined.
2. Plant and Ooze should be combined.
These first two I think are the best. Not overpowered and are thematically very similar. The rest will probably provoke more discussion.
3. Air, Fire, Water and Earth outsiders should be combined under Outsider (Elemental)
4. Humaniods should be combined as well into one large group.
I believe the outsiders would not be overpowered, however the humaniods may be. I haven't done extensive playtesting with that variant.
Finally, two small changes to the Pathfinder favored terrain addition to the Ranger.
1. Dungeon and Cave should be combined into a general Underground.
2. Boats and Underwater should be combined into a general Water.
These two changes are due primarily to confusion. (ie. - Many dungeons start out as caves and are later expanded upon)
What does everybody think?
Well, one thing to consider is that the Animal type isn't just for regular animals, it also includes the following:
Dinosaurs
Dire animals
Rocs
Swarms (Bat/Rat)
However, vermin are so few and rarely encountered, and thematically appropriate, that it could be added without an issue.
Humanoids is an odd one. I guess it's there because they probably make up the majority of the NPCs and people that are found in any civilized area. Meaning, an "urban" ranger in a mostly city game would get a bonus against 90% of his opponents with one choice otherwise.
However, I can't really see why there's that much difference between some of them. Maybe break it down like this:
Humanoid (Aquatic)
Humanoid (Goblinoid)
Humanoid (Reptilian)
Humanoid (Gnoll --> why this guy isn't just a monstrous humanoid already is beyond me)
Humanoid (Dwarf, Elf, Gnome, Halfling, Human, Orc)
This would fit better in my sensibilities.
With regards to Outsider (elemental)... how does that jive with the Elemental choice? Or you mean, you are combining all 5 of them (the four outsiders with the elemental type).
The terrain changes are fine by me. I mean, losing your bonus because you happened to go "under" the water, or "deeper" into that cave feels a bit off. That's kinda like saying "Urban (outside buildings) and Urban (inside buildings)".. you are in an urban area, you should get the bonus. Same with water and underground.