Factions or Nightfall?

Hi i just recently bought g wars prophecies and i want an idea on what next i should get. You see, what interests me most about factions is The assassin character. Are these characters good? What ive noticed about nightfall is the quests and new characters. But i really dont know which one to choose. Please explain what theyre like and what some of these new characters do. Thank You

it is all about how you want to play. If you are more of a pvp person, go wit hfactions. If you like pve more, Nightfall is for you. Factions was meant for the pvp portion of the game, pve is short and straight to the point.

I like fighting others and i like role playing, i like em both thats why im having such a hard decision

Or you can get factions for pvp and GW:EN for pve