Ok they have all chosen VERY high end monsters?
Travesty is VERY hard with a single tamer. If you dont beat her quickly after she teleports she can do her spawn thingy OVER and OVER.
Grizzle might be easier but again will take a LONG time and some very descent skills as a tamer.
What is your Temp?
Mage / Tamer, Bard / Tamer, Warrior / Tamer?
Simple high end monster is a Sucubi, easy gold and some OK items.
The underworld has mini champs for ingredients and stuff.
Melisande (better with a partner)
you are much better off finding a freind to go out hunting with will make the game more enjoyable and hunting is MUCH more effective.