Why should the ranger even be compared to a paladin smiting. I don’t thing a ranger is supposed to be doing damage like a paladin. They have many other useful abilities. Now I do like favored for because it does not burn a spell slot and I can use my spell slots for other things.
Level 2 ranger has:
1 level of spellcasting (known spells, not prepared)
1 fighting style
2d10 HD
Martial Weapon Proficiency, Medium + Shield for armor
Favored Foe (or FE)
Natural Explorer
3 skills
Level 2 paladin has:
1 level of spellcasting (prepared, entire list)
1 fighting style
2d10 HD
Martial Weapon Proficiency, Heavy+Shield for armor
Lay on Hands (10 HP)
Divine smite
Divine sense
2 skills
Subtracting, the Paladin gets:
Prepared instead of fixed spells
Heavy armor
Lay on Hands, Divine Smite, Divine Sense vs FF+Natural explorer+1 skill
Divine Sense and Natural Explorer are both exploration abilities that depend on the game's plot to determine if they are awesome or useless. Lay on Hands vs 1 skill is an interesting tradeoff; in one case, it is the 5th or 6th best skill you have and in the other it is the ability to miraculously heal someone by touching them. We can call those a wash.
Heavy Armor means a Strength-Paladin is better than a Strength-Ranger in AC, but has no impact on Dex-Rangers vs Dex-Paladins. I'll throw that in as rounding error.
Divine Smite is a meaty ability that has narrative impact when used. FF, meanwhile, is rounding error when used.
That, plus the fact that someone said "when is action free damage crappy", is why I'm comparing those two. Action free damage that has extra requirements and has nearly no impact even when you use it doesn't suddenly become non-crappy just because it is action free damage.
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I mean, even if the Ranger didn't have its problems, FF is a
bad feature design. It has some narrative impact at level 1, but soon it becomes more mechanically fiddly than it has impact.
Its damage fails to scale very fast, but you still have to check concentration (are you using it), determine when it ends, remember who it is used on, apply it once per round not per attack (so you can't just automatically roll the dice). In my experience, people are going to forget they have a long concentraiton buff up (say, Pass without Trace) at least once and use it, and a non-zero amount of that time nobody else will notice, so you'll either should have lost Pass without Trace because you FF but you didn't, or you accidentally lose Pass without Trace by using FF. And keeping
track of that isn't worth the narrative impact of the ability when you do use it!
And HM does a better job of the narrative space FF is in, and shows up 1 level later.
If we compare it to other classes, it is lackluster. If we consider it alone, it is lacking.