Two problems here.
1) The ACo attack is better than the TWF off-hand attack. It (potentially, depending on beast) does more damage and has other effects. The ranger can raise his TWF damage, but that's at the cost of a feat.
Not quite, and when it is superior, it isn't as often as you think:
- TWF gets the damage boost for the Fighting Style, not taking a feat. It's free, and worth up to +5 per attack due to off-hand bonus. Figure +3 at 2d assuming a 16 starting stat, which will almost certainly be 20 at 8th level with two Ability Improvements. So you have gain a (+5 to hit) 1d6+3 (6) off-hand attack as a bonus action at 2d level, which rises to (+8 to hit) 1d6+5 (8) at 8th, plus potentially boosted by +1d8 (4) once per turn with Colossus Slayer starting at 3rd level. (All .5 damage rounded down for simplicity.)
- Versus the beast attack, which gets the proficiency bonus to attack and defense. Picking a few likely choices from the PHB:
Boar: 3rd (+5 to hit, 1d6+3 (6) damage) to 8th (+6 to hit, 1d6+4 (7) damage), can do extra 3 damage on a charge. Call it equal.
Mastiff: 3rd (+5 to hit, 1d6+3 (6) damage) to 8th (+6 to hit, 1d6+4 (7) damage), DC 11 to knock prone. I'd call this slightly inferior at all levels.
Panther: 3rd (+6 to hit, 1d6+4 (7) damage) to 8th (+7 to hit, 1d6+5 (8) damage). Can knock prone on a pounce (DC 12). This is slightly better than TWF at 3rd level but slightly worse at 8th.
Poisonous Snake: 3rd: +7 to hit (8th +8 to hit), 3 (8th: 4) damage plus either 2d4 (5) on a failed DC10 save or 2d4/2 (2) on a successful save -- average 6 at 3rd and 7 at 8th given a 50/50 save . That's better accuracy at 3rd but equal or inferior in damage, plus its dependent on a fairly easy save.
Wolf: 3rd (+6 to hit, 2d4+4 (9) damage) to 8th (+7 to hit, 2d4+5 (10) damage), advantage if attacking with an ally, trip on DC11 STR failure. This is the superior companion choice of the PHB options -- but I'd argue not absolutely superior give the other tradeoffs between fighting style and companions.
... And of course the TWF off-hand attack can't be killed, immobilized, held, charmed, or any of the other things an animal companion is exposed to -- at 3rd level, the best choice above is AC 15 with 12 hp, rising to AC 16 with 32 hp at 8th level. The Hunter doesn't have to worry about defending his class ability, though the Beastmaster gains a distraction and additional hp sink, for a little while.
Overall, I think that makes a TWF bonus attack equal or slightly better than a beast attack under most conditions -- which then swings clearly in favor of TWF if Colossus Slayer or the use of large weapons via the Dual Wielder feat come into play -- but
only if the beastmaster is getting the beast attack as a bonus action, not as an either-or as written now.
2) It makes choosing TWF an inferior option. All other fighting styles now provide a bonus in addition to being a beastmaster, while TWF does not. The ranger can still get his +2 to archery, or whatever.
Not really; it makes it still a reasonable choice. Consider:
- The archery +2 to hit only applies to archery attacks; it doesn't apply for beast attacks. It doesn't grant an extra attack.
- Duelist +2 to damage doesn't apply to beast attacks; it doesn't grant an extra attack.
- Defense (+1 AC) is the only choice that applies all the time, but it doesn't affect attacks. TWF can match it by taking the Dual Wielder feat later on (also gaining the ability to dual-wield 1d8 weapons instead of just 1d6, which bumps all of the comparisons above by a point of damage in favor of TWF).
Frankly, in terms of offensive ability, the three styles above are basically inferior to TWF as far as the ranger is concerned since only TWF enables a fully capable additional attack. The beastmaster who takes TWF only makes the tradeoff when the beast attacks and retains full attack otherwise; a non-TWF style gains an attack to equal the TWF'er beastmaster ... and is still likely a bit behind a ranger with the same or TWF fighting style who takes the Hunter approach and Colossus Slayer ability.
Yes, the TWF option I proposed is a bit of a kludge, and I'd love to hear alternate suggestions, but I still think it's the best option thus far, in terms of balance.
My nomination is this:
Change the mechanic to read: "You gain a bonus action to direct your animal companion to take the Attack, Dash, Disengage, Dodge, or Help action. On a turn where you do not direct your companion, it continues to perform the last command given until that is no longer possible, at which time it takes the Dodge action until directed otherwise."
At 7th level: "On any turn when you and your companion use attack the same opponent, you each gain advantage on your first attack."
It doesn't make the choices equal, but makes them close enough to be equivalent that there's a more reasonable choice between the two than there is now.