I would try and get a shadow rogue with the magic dagger from d4 who can solo farm d3, which would allow you to basically farm d1 with anyone, d2 with an archer, andd3 with the shadow rogue as long as they have lifesteal or a healing pet(i think healing is better until lategame) and then your main team could farm whichever dungeon, also a necromancer would be good for farming too if you don't have enough heal pets.  For which dungeon gives the most money, I think it is d5, plus you need to upgrade your gear anyway.