IMO, classes that fit the "lawful good" RP perspective, other than Paladin and Monk, which you do not want:

- Cleric of a Good Deity
- Fighter
- Wizard (Abjuration or Divination)

That's it... Barbarians for sure can be good, but they're too chaotic, same for Rogues, Bards and Sorcerers. Druids and Rangers gravitate heavily towards balance and chaos, they have little care for laws of civilization.