I (like half the people on these boards) have a homebrew ranger that amounts to a complete overhaul, but here are the high points:
- Spellcasting as a subclass. This is not an intrinsically magical character archetype.
- Marking quarry as a core feature. Distinguish the ranger from the fighter, barbarian, and rogue by playing up the "singleminded hunter" theme mechanically. Favored Enemy is an optional substitute feature: basically, "you automatically have this type of creature marked, but you can't mark other creatures".
- Expertise. In Survival at a minimum. Under no circumstances should bards be better trackers than rangers.
- Class features that emphasize perception, mobility, endurance, and knowledge.
- Constitution as a save proficiency. That the core ranger doesn't have it is just criminal. I'd go Dex/Con because I don't really care much for the "good save/bad save" dichotomy, but if you do, Str/Con or Int/Con.