I'm not a game designer, but I agree with some of the criticism of rangers that's been expressed here. I've never really been comfortable with ranger spells, mostly because they seem to have been tagged on without really adding anything: usually, by the time the ranger has access to them, power levels have increased to the point where they don't offer any real benefit. Favoured enemy seems too specific for a particular role to be such a key feature of the class.
See, I disagree with taking spells out of the ranger. First of all, doing so really does just push them to just being a fighter or rogue, which I don't want. Secondly, I feel a better solution is more ranger exclusive spells that are designed better. No body looks at the paladin spell list and says "Well, by the time I get these they are all worthless, paladins just shouldn't have spellcasting"
One thing I've seen that I think works pretty well is giving them more spells that make weapon attacks, like a slightly rewritten Steel Wind Strike (which should never have been designed to make it better for wizards than it is rangers) and more and better spells for archery, like improving Lightning Arrow.