OK! I'm back from 10 days of vaca. Went to Colorado for some of it. Was nice. But I digress/more on that later/different threads. SO...I can actually catch up of everything...apparently they went and threw out some psionics while I wasn't looking.

But again...digression...
HOW ABOUT...as @
kerbarian rightly points out the importance of the [ANY] class having that mesh of meaningful mechanical advantages WITH/while maintaining a distinct flavor, instead of a "Favored Enemy" (even if they were going to increase in number as the ranger leveled), per se, and instead of a sweeping "bounus to everything" like Hunter's Mark [or practically everything, a la 1e] we (as is wise for so many things in life) moderate...take it in moderation...find the reality in the middle...
What if "Favored/Preferred/Advantaged/Whatever Adjective Quarry/Prey/Foes/Whatever Noun" were a feature of combat bonuses that you add to at a significant rate of expansion, like every level or every other level. The usefulness/foes, that is, NOT the bonus just endlessly "+'ing up (though that might increase at a much slower rate).
Those Poor Unfortunate Foes:
In their role as defender of their respective civilizations and/or wilderlands, the ranger is adept at sizing up and taking advantage of any weaknesses they perceive in the enemy creature. This feature requires some time, often including multiple run-in's with the creatures in question and observation, study, and/or training or learning from peers about these particular creatures effectively. Further, they are astute and intelligent enough to apply this assessment to any of the creature's race, allowing them a bonus to hit and damage fighting such creatures anywhere, in any number.
Beginning at level 1 the ranger selects such a creature/race of the
Humanoid (up to ogre or troll) or
Animal (including monstrous or giant varieties) type. An additional Humanoid or Animal foe is chosen at 2nd level. Following that, the ranger adds additional Unfortunates to their list of Foes every other level [each even level].
The ranger is +1 to hit and damage when attacking these creatures with melee or ranged weapons. The ranger is also +1 to any tracking or lore roles pertaining to the creature, their culture or behaviors and gains 1 language for every 3 types of creature they have amassed as their Unfortunate Foes, if there are creatures that possess a language. This bonus increases +1, for attack and skill rolls, every 5 levels thereafter.
At level 5 the ranger may begin studying/selecting creatures of the Fey or Undead type. At level 7 or above, the ranger is free to select monsters with the Giant or Dragon type. The DM is free to add or swap out creature types, within this general framework (e.g. no more than 2 or 3 creature types at a time, more powerful creatures added at higher levels, etc...), as best befit their world and campaign. If you run a game overrun with Aberrations or Demons or Elementals, then it makes sense the ranger would be permitted that creature type at 5th or 7th level, if not from first.
At 20th level, you're looking at a ranger who has amassed (throughout their adventuring career, as played in game) +5 bonuses to hit, damage, tracking and lore rolls against 11 creature types. Not really game breaky from what I can see, and lets players [including DMs] "build" their rangers to their specifications, i.e. They aren't all the same, hunting/doing the same thing all of the time, but gaining their own life experiences and using their intelligence and expertise to apply to what they -repeatedly/consistently- face.
Those that want can "Aragorn it up" by choosing with a list of: Goblins, Wargs, Trolls, Wraiths, etc etc...
Those that want Ginsu Blades of Doom can choose every humanoid in the book.
Those that want "Giant-killer/Dragon-slayer/Vampire Hunter" can choose every creature of a particular type that they can.
But I think this nicely blends old school sensibility without being "99% of humanoids & ALL giants all the time" and the newer school "we need a bonus against everything all of the time or we're no good/not as good as the fighter". You are "good" [and
increasingly "good"] against an ever-widening sphere of creatures. But you'll never be "as good against everything."