First Which Server for the quest
Second you have to choose between them (Note Angela quest requires u to have your OWN space craft {Idk about Venus} )

Angela Skills Info : http://wonderlandonline.wikia.com/wiki/Angela
Venus Skills Info : http://wonderlandonline.wikia.com/wiki/Venus

I believe Venus can burst but Angela cant
Angela is more used than Venus
Venus's support skill is similar to sleep
Angela's support skill is Healing similar to Cure Spell and Recovery

The Choice is yours :D

Sorry but i cant provide help just gave u ideas of each pet