Ranger

Beast Master

Source: Player's Handbook

Says what it is on the tin. You area ranger with a cool animal companion, your choice from a variety of pretty standard creatures or a magical primal creature which is alot cooler and overall better mechanics.
The Features you get are pretty underwhelming if i really wanted to play this kind of of class i would suggest going with the Beastheart instead.
BUT if your restricted to content i would defiantly work with the player to provide some much needed buffs and more interesting mechanics to this subclass. Maybe some coordinated attacks or some unique magic items and give some options for scouting and tracking with your companion as well as being able to mount them for travel or combat AND some cooler more powerful options for your companion .

2024 Revision Available

The revision basically just streamlined the options, no more animals only primal beasts. still has the same issues and i would still have the same edits to make it cooler.

Coven

Source: Hexbound, Pg 30

A cool subclass that's kinda like they took the primal beasts from beast master then built all the mechanics around it. you choose one of three nature gods/spirits/patrons whatever the setting your playing in helps with, the elk is all about magic boons, the snake is defensive and the wolf is for meele attackers. the boons they grant as features are pretty good although i think i would make the snakes defensive boons more active than requiring you to be under certain levels of HP. if you were looking for a Ranger who is REALLY in touch with the spirit of nature this is the subclass to run.

Drake Warden

Source: Fizban's Treasury of Dragons

Is like beast master but better cause its a Dragon. the features are more themed and on brand but you are restricted to a dragon *Gasp*. i think the subclass is pretty solid but as a DM i would allow flight much earlier than level 15 like common?! 7th level when the dragon gets wings would be when i would recommend but when some Races can get innate flying speed?!?! whats the point just give your player flying speed! don't be scared. aside from that i would work with the player to get some some magic items to bolster this subclass further.

Fey Wanderer

Source: Tasha's Cauldron of Everything

An overall solid class for the ranger wannting a Feywild twist, perhaps a character who is from the feywild or one who was stolen away by meddling fey. it has some good offensive features, some good non-combat features and some cool themed spells. i would allow dreadful strikes t proc on all attacks not just once per turn and i think Fey reinforcments could be altered more so its not just a free spell cast but something more eventful and fantastic, perhaps a unique fey tied to the ranger's story. it also has some cool physical effects for your character and i am a fan of those.

2024 Revision Available

I honestly don't think they changed anything, just the wording, which is fine cause it was a cool class to begin with.

Field Researcher

Source: Floral Dragon Sub-Classes, Pg 4

Overall pretty solid class, has some simlar beast to Fey wanderer but more on Intelligence skills than wisdom. Gives you an extra attack as a bonus action and has the HUGE boon to give allies advantage on attacks or checks as a reaction. while in combat this is fantastic, allowing rouges to get sneak attack. giving heavy hitters better odds while still having your entier turn to yourself this is massive for non-combat basically giving anyone advantage on any check they make so long as your within 5ft. i would restrict this to only work on skills you have in common with the other player otherwise you might as well call this subclass the 'Advantage Battery' or perhaps put a limit on its uses to be the same as proficiency bonus or even half that.
You also get some cool stuff relating to plant and animal summoning. this is very much a support tunned subclass but what a support it is.

Gloom Stalker

Source: Xanathar's Guide to Everything

A Pretty cool class with features based around striking hard fast in the first round of combat. but fights rarely last one round and so the following rounds you are missing out on alot of your features. The sub-class has some cool features that give you a redo on missed attacks, some extra saving throw proficiencies and so on, I would change a few things like rather than a boost to initiative just give them extra movement speed, very solid overall with a few lacking features.

2024 Revision Available

Overall quite a few buffs turning a solid class into a great class and would defiantly recommend this one over the first run. Dreadful strike does more damage and can be used multiple times between long rests rather than just the first turn of combat. Stalker's fury has some extra effects that stack onto your Dreadful strikes now rather than just being a re-do of a missed attack.
I would still remove the initiative bonus and just make the extra 10ft movement speed permeant. as well as change the wording slightly for Umbral sight to specify you are invisible to all creatures relying on non-magical sight (but Including magical dark vision) to see you in darkness.

Horizon Walker

Source: Xanathar's Guide to Everything

A REALLY cool idea that just fails to hit the mark with alot of its features, luckily because alot of the features are so close to being good there is little work to be done to make them good and fun.
Detect Portal: really cool unless you are in a campaign without a emphasis on portals. Increase its range higher than 1 mile AND, When a creature attempts to use a spell or ability that would have perform planer travel you ca use a reaction to stop that effect and prevent the creature from planer traveling for 8 hours. Can use this a number of times equal to half proficiency bonus rounded down recovering on a long rest.
Planner warrior: As part of your attack action you can convert your next attack to be entirely force damage and its damage is boosted by 1d8 which increases to 2d8 at later levels. you can use it a number of times equal to WIS modifier recovering on a long rest.
Ethereal Step: as a Bonus action you can enter a special state of Ethereness, for 1 minuet your attacks strike foes weather they are on the material or ethereal plane and you are able to see foes on both planes, You can also use half your movement to step into or out of the ethereal plane, If your minuet runs out while you are in the ethereal plane you are shunted out taking 4d10 force damage. You can use this feature a number of times qual to half your wisdom modifier rounded down.
Distant Strike: increase teleport distance

Hunter

Player's Handbook

A Ranger that gets special skills in the form of special moves to fight off single targets or groups, cool on paper but none of these features are too dramatic…on their own! I would just ditch the requirement of choose one option at each level and just give the ranger all the available options when they become available at each level.

2024 Revision Available

Done dirty, options removed and the later level features were replaced with very stale and generic features. i would still run the original form of hunter.

Monster Slayer

Source: Xanathar's Guide to Everything

Text

Swarm Keeper

Source: Tasha's Cauldron of Everything

Text.

Urban

Source: Guide to Drakenhime, Pg 167

Text