What do you think of this:
A scout ranger gets Favored Terrain on all levels he would get Favored Enemy, and Favored Enemy on all levels he would get Favored Terrain.
Favored Terrain seems like a less powerful but more useful ability to me, so I think they should be balancing each other out.
instead of scout, how about explorer? scouts already a rogue archetype. mechanically this isn't exactly much but...wait, this makes for a pretty awesome world walker qualifier.