Reasoning
Warcraft Tavern's Hunter guide recommends Leatherworking because Hunters start in leather and Forever adds improved armor kits with stat bonuses usable even on early greens. Engineering is the other pick because it lets Hunters craft their own ammunition and scopes, and Forever adds new schematics and Engineering trinkets on top of that. A second, unverified source agrees Leatherworking is core for Hunter but suggests pairing it with Skinning while leveling for material self-sufficiency and a haste-related skinning perk, switching toward Engineering at endgame for its trinkets and utility. Source picks: Warcraft Tavern Hunter guide: Leatherworking + Engineering; Koroboost (unverified): Skinning + Leatherworking while leveling.
Confidence note
Analysis built from sourced profession facts