Paladin is the only healer on alliance side that provides meaningful DPS/mitigation buffs for physical DPS classes. Judgement of wisdom is also quite useful for hunters.

Otherwise, probably druid for fast boss runs using stealth and feign death. Though, since in classic it seems you don't enter combat with mobs automatically when your party members engage, I wonder if you could just pull mobs using standard hunter tricks, run your team past and park it around a corner then feign on the hunter to reset the mobs without even needing stealth? Might be possible.