So for classic I think about lvling mainly in dungs and farming gold in dungs later in the game. For my team i would take a prot paladin, Holy priest, lock, mage and a 3rd caster. The holy priest will be my main for solo raiding afterwards. I didn't main Priest back in vanilla just a paladin so I don't really know its value from back then

The question is would a shadow priest add more value to the team than either a second mage or warlock?