My thoughts and two pennies.
1> There are plenty of versions of rangers. When I look at my books of ranger kits, prestige classes, or dragon articles then I find there are plenty of different rangers.
Many of those types of rangers like the Desert Ranger, Urban Ranger, or Glacier Ranger are similar to each other with the Wilderness part pulled off and bolted on in a new version. You shift a few skill and feat choices and you create the Sea Ranger.
Further to this, I see almost the same amount of the exact same bolt on and snap off bits for all the other classes. I've seen Mountain Wizards, Ice Clerics, Primitive Fighters, and other variations on the main theme.
This suggests to me that the Forest or Wilderness concept to the Ranger is like the Criminal idea to the Rogue. If you want a 'classic' forest Ranger then choose the Forest theme but if you are doing a nautical campaign you might replace the Forest theme with the Sea theme.
This now allows value to the Ranger concept as they can start adapted to their environment (instead of explaining why they are dressed in green tights and standing in the middle of a desert ~ cactus? ). It also allows other classes to choose to pick up any of these 'Terrain Themes' at the start if they want to make a Desert Priest or Sea Warrior.
When a ranger levels up they could then select with their 'theme' choices to pick up additional 'Terrain Themes' or the design of the Ranger class may allow a 'free' Terrain Theme choice at certain levels.
2> Animals, how I love my Ranger pets and how some people loathe them.
Some people want a pet and some people don't. Some people want to start with a pet and some people would like to put it off.
Pets, Animals, Familiars, Divine companions, and other such things are again something that is not unique to the wants of Rangers.
If you are Cleric of the Forest then you might want to have a Wolf or Bear following you around even though you are not a Druid. If you are a Fighter then maybe you are a Bestiario that fights with War Dogs beside you while riding a Warhorse.
If you don't want an Animal then maybe you'd like a Brownie or Elf to stand beside you in battle (1st ed rangers did not just attract animals to accompany them but non-humans also). If you are a Wizard then maybe you'd like a Shield Maiden or Yojimbo accompanying you on your travels and adventures.
A universal idea that has appeared in different classes and at different levels speaks to me again of the concept of 'theme'.
This again works well for the 'Ranger' who can then trade the 'Animal' or 'Companion' theme for a different theme if the GM doesn't want pets in their campaign or if the player prefers picking up 'mystic' or 'noble' as an alternative choice.
A classic 3e core Ranger might choose 'Forest' as his first level theme and 'Animal Companion' as his 5th level theme. He could even pick up 'Mystic' as his 3rd theme to give access to limited spells at higher levels.
3> So if we pull those parts off of a Ranger, what is left? If you remove the themes of 'Terrain', 'Companion', and 'Mystic' (my stand in for limited spell access without knowing more of the system) then what is left to be the Ranger?
+ There is the Damage Bonus (Favoured Enemey or Anti-humanoid Giants).
+ There is tracking
+ There is Ambush (bonus on surprise checks), Stealth, Mobility
+ Preference for light armour and certain weapons (though not mandatory in 1st ed where the selection was fully the same as Fighters).
+ Possibly a dedicated weapon specialist though this seems to me more of a Fighter concept then a Ranger.
This would suggest going with a Hunter/Special Ops approach. Rangers are not just ordinary woodsmen or warriors trained to stand firm in the line of battle. They believe them selves to be the 'Best of the Best'. One or two rangers can work independently or as part of a team to round up Poachers, Lead forces through hazardous terrain, Find enemy formations, and hunt down dangerous animals.
Personally, I'm not a fan of the 'Favoured Enemey' approach. I've been burned too many times by GMs while playing a ranger (weird how undead and dragons stop appearing in the campaign when you are dedicated to killing them). I much prefer the Avenger/Ranger 4e version of quarry or the PF Inquisitor's Bane weapon and Judgements (though I doubt the fluff would fly with most of the Ranger crowd complaining of magic getting in the way of their 'pure' rangers).
For the Hunter theme to work there are two ways to approach the problem.
Option 1: The Hunter has to select a target to go after and they get bonuses on damage (or some ability) against the target. The good of this idea is that you can 'trigger' this in any fight (depending on how skills work, it may even require a 'skill check' to get it to work). The bad of this is that players might want to know why your Ranger who has never met a Quaggoth before knows how to hurt them so well (there is also a heavy 'its magic' association that people might want to avoid).
Option 2: The dedicated weapon specialist. You've given up medium and heavy armour because you are just so focused on your weapon or weapons of choice. Fighters are generalists that can be good with any weapon but you've spent years dedicated to one weapon (bow, double blades, single blade, daggers, axes, spears, whatever). The good is that as long as you are using your favoured item then you get your bonus to damage (you are the 'ace archer' or the 'kensi blade master'). The bad is that Fighters/Warriors may be upset that your ranger using that one weapon can do more damage then they can (the balance being you are stuck in light armour where they are not).
That is enough 'chew' for one post.