So, I'd be remiss if I didn't post my first snap impressions on everything the Ranger got in the new UA: Class Feature Variants document. Rangers got more than anyone in this (as may be expected), and a lot of it is either very good as is or at least on the right track.
Deft Explorer (overall rating) - Even with some things that need ironing out before final publication, this is already much better designed than Natural Explorer was or ever will be, with abilities that are always beneficial. Definitely on the right track here.
Deft Explorer Options
Canny - Giving Rangers the ability to Expertise a skill that they really should've had all along, plus extra languages. Nice start, though this seems to be an option that the Ranger should be allowed to take more than once, each one for a different Expertised skill and set of languages. That'll be a suggestion I make when filling the survey.
Roving - Extra speed plus actual swimming and climbing speeds. Good.
Tireless - Free temp HPs for WIS mod per day is great. And decreasing exhaustion level on short rest, which is merely good on a straight Ranger, just made Ranger the perfect one-level dip for a Berserker Barbarian. Expect this one to change somehow, perhaps given a Ranger level requirement.
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Favored Foe - Well, on the one hand, WIS-mod castings per day of a concentration-less Hunter's Mark is certainly stronger than Favored Enemy, both for combat and for tracking purposes. If simply grading on performance, this is sky blue, easily. But, I have to ding it a bit on design principle. For one, Hunter's Mark is still going to require bonus actions to tag and switch enemies, which doesn't play nice with a fair number of Ranger builds (dual-wielders, Beast Masters, Horizon Walkers). And second, Rangers getting all of this at Lv. 1 makes this prime one-level dip bait for a number of other classes (Monks and Moon Druids spring to mind), so that'll have to be addressed before publication, somehow. Thirdly, it would help to designate which level Hunter's Mark is actually cast at with this feature; which is important in determining its duration.
EDIT: Just a quick brainstorm ... how about the concentration-less Hunter's Mark 1/day at Lv. 1, and then at Lv. 6 (when the Favored Enemy Ranger gets another FE) it increases to WIS-mod/day?
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Fighting Styles
Druidic Warrior - The obvious one is Shillelagh to make a fully WIS-based melee Ranger, though that locks you into the quarterstaff (which isn't too bad, because Polearm Master + shield). And then there is, of course, Guidance. If you're primarily non-DEX melee with a decent WIS, there's also some decent ranged cantrips available as secondary modes of attack (Produce Flame, Frostbite) or the AoE Thunderclap.
Blind Fighting - EXTREMELY BROKEN as currently written. Spellcaster with Darkness or Fog Cloud + this = All the advantage you could ever want. Now factor GWM/SS in the mix. This one needs to be nerfed, if not omitted entirely in an official release.
Interception - Rangers get a style to defend others with, and it's at the very least better on the action economy and more consistent than Protection, if not better overall.
Thrown Weapon Fighting - Makes an axe-chucking Ranger a viable build. Might also be worthwhile for any STR-Rangers to develop an easy ranged option if they're forced into ranged combat.
Unarmed Fighting - Obviously niche, though very good in its niche. And hey, since Athletics is a Canny option, an unarmed grappling Ranger is suddenly a pretty neat possibility.
Spell List Additions (notables)
Entangle - AoE entangling. Unlike Entangling Strike, this doesn't give Large creatures advantage on the saving throw, though since Entangling Strike adds damage to your typical attack it's probably still better against a single enemy. Decent addition, nonetheless.
Searing Smite - Rangers get a Smite spell that was completely useless for Paladins. For Rangers, though, it depends. It's not a bad choice for Rangers who take Favored Foe instead of Favored Enemy, since in that case it won't compete with Hunter's Mark for your concentration (though it still does for your bonus action). If you're still taking Favored Enemy, forget it.
Aid - Extra HPs without concentration is good.
Enhance Ability - Huge. Bull's Strength if you're one of those new grappling Rangers that are now suddenly quite appealing. Cat's Grace to enhance Stealth and initiative, or Owl's Wisdom to enhance Perception and Survival. Very, very welcome addition, though 2nd-level was a pretty loaded level for Rangers already. But that's why Rangers have Spell Versatility now.
Warding Bond - Rangers get an ally protection spell that's pretty solid.
Blinding Smite - Wow, this is actually one of the Paladin's better Smite spells Rangers just yanked. Very nice addition for melee Rangers who didn't have much spell love before.
Revivify - Woo, Rangers can raise dead now. This is especially big for Beast Masters who no longer have to go through the trouble of replacing their pet if (or most likely when) they die.
Death Ward - Saves you from KO or instant death without concentration. Good one. And a prime spell to take advantage of the Beast Master's Share Spells, too.
Awaken - At Lv. 17, you finally get your own superior animal or plant companion to the Beast Master's, even if you aren't a Beast Master. As many of them as you want, too. Will definitely be many Rangers' new favorite 5th-level spell.
Greater Restoration - Remove an exhaustion level or a number of pretty crippling conditions. Interesting this got added to the Ranger and not the Paladin ... but hey, you'll take it.
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Spell Versatility - A bit controversial at the moment. I will say that of the classes that get it, the Ranger is the one who definitely needs it the most. It fits them thematically, and to a certain extent it makes up for the fact they're not a prepared caster like I felt they should've been the whole time.
Spellcasting Focus - Woo, no more component pouch. You can use a druidic focus now for your no-cost material components.
Primal Awareness - Hands-down superior replacement for Primeval Awareness, giving the Ranger a suite of spells that they can use to garner much the same info they would've gotten from Primeval Awareness. Spells that absolutely fit the Ranger, but spells that Rangers wouldn't have used one of their precious and limited spell learning opportunities on. Now they get them for free and can even cast them once a day each without using a spell slot. Love this one, it can stay as it is.
Fade Away - Bonus action invisibility for a round per short rest to replace the highly situational Hide in Plain Sight. While I admittedly appreciate the old feature's potential for ambushes and long-term scouting, this replacement is just so much more consistently useful it's not even a contest, really.
Ranger Companion Options - Considerable improvements over the standard Beast Master fare, with a lot of the things oft-requested as fixes or buffs. Better hit point scaling, easy restoration after it dies (with a 1st-level slot), bonus-action abilities from the start.
(On a completely different note, it's interesting that the introductory paragraph basically codified animal companions that any Ranger, not just the Beast Master, can gain from the Animal Handling skill or the Animal Friendship spell.)
