I’d argue that Bounty Hunter is META for any unit who can class into it.
Let’s analyze this statistically.
Bounty Hunter’s promo gains are +3 HP, +4 Strength, +1 Skill, +2 Speed, +2 Defense, +1 Resistance, +0 Magic. Its class skill is Thunderstorm, granting +3 damage, +20 Hit and +10 Crit as long as the user’s weapon out-weighs the foe’s weapon.
The two classes that feed into Bounty Hunter are Mercenary and Fighter.
Mercenary’s alternative to Bounty Hunter is Hoplite, which has promo gains of: 4 HP, 2 Strength, 3 Skill, 2 Speed, 2 Defense, 2 Resistance, 1 Magic. Its class skill is Triangle Adept, doubling WT bonuses and penalties.
Fighter’s alternative to Bounty Hunter is Warrior, which has promo gains of: 5 HP, 3 Strength, 3 Skill, 2 Speed, 1 Defense, 1 Resistance, 1 Magic. Its class skill is Reckless, granting +4 damage if the foe can counterattack.
First of all, Thunderstorm is very easy to use. Steel Blades and Steel Axes weigh 14, and both are fairly easy to acquire; however, few other weapons weigh 14 or more (Brave Lance, Brave Axe, Hammer, Battle Axe, Heavy Spear, Greatlance, Greed, Arbalest and Siege weapons). This means that in almost all relevant circumstances, Thunderstorm is active; the only weapons on the 14+ WT list that are encountered among enemy forces with reasonable frequency are the Steel Axe, Greatlance and Battle Axe, and the Bounty Hunter class has options to WTA these weapons regardless. As such, Thunderstorm effectively has 100% uptime, as the only cases where it isn’t active are cases where it is already winning regardless.
Thus, when Thunderstorm is factored into Bounty Hunter’s promo gains, it effectively has a Strength boost of +7. This is monstrous. OHKOs are a lot more commonplace now, and +20 Hit means that with a decent Skill stat, which many of the Mercenaries/Fighters in the game have, Bounty Hunters are in contention for the single most accurate class in the game, making them good at dealing with enemies on terrain or when Sandraudiga is on the map with her 10 Authority.
When compared up against Warrior, Bounty Hunter simply does what Warrior does, which is have a massive Attack stat, but better. Both effectively give +7 damage between their stat boosts and class skill, but Bounty Hunter does so more efficiently, in addition to offering extra accuracy and crit. Additionally, Bounty Hunter offers WT flexibility, whereas Warrior gains bows, which have limited use, and tomes, despite most Fighter-line units having inferior magic that stops them from using them particularly effectively.
When compared up against Hoplite, Bounty Hunter holds up despite Hoplite being meant to be the bulkier option. Despite Hoplite seemingly being meant to tank, Bounty Hunter is only behind by 1 HP and 1 Resistance, neither of which are particularly large losses. Additionally, Hoplite’s advantage in Skill is effectively moot because Thunderstorm does way more than 2 extra points of Skill will ever do, considering Thunderstorm is effectively 100% active. Furthermore, Hoplite’s Triangle Adept usually hurts it more than it helps. Doubling WT modifiers means that winning WT just means taking an already won matchup and making it slightly better; anyone can win a winning matchup so there’s no particular need to double down. On the flip side, suffering double WTD penalties is very dangerous, as it leaves your unit as a sitting duck to take huge damage; in the late-game, enemies in classes that offer full WT coverage like Hoplite and Great Knight often come with full WT coverage, meaning that your Hoplite is automatically losing any matchup against them; even those without full WT coverage will often run coverage for both or all of their weapon options, to severely limit what Hoplite can do.
Even in terms of caps for postgame, Bounty Hunter is still better. Aside from Hoplite being completely crippled in the caps department (with 26 Strength/Speed), its supposed physical bulk in 25 Defense is not of any value, because Bounty Hunter also caps at 25. Bounty Hunter meanwhile has only slightly less Skill than Hoplite (27 to Hoplite’s 28), but has +3 Strength for a cap of 29. Against Warrior, their caps are more or less the same; Bounty Hunter is behind by 1 Strength (29 against 30) but has +1 Skill to compensate (27 against 26), and +1 Defense (25 to 24) in exchange for -4 Magic (21 against 25), but Magic never mattered to begin with.
The conclusion? Bounty Hunter is very, very strong. It is the META for any unit who can class into it, because the alternative are just a whole lot worse. Phobos, Fango, Jane, Hestia, Fructouso, and to an extent, Fighter-line Pheme, should always promote into Bounty Hunter whenever possible. The class is just that good, with Thunderstorm being a large chunk of what makes it good.