Nightfall
Nightfall takes place on the continent of Elona and spans the regions of Istan, Vourna, Vabbi, The Desolation and Realm of TormentPlayers starting out in Nightfall join the Order of the Sunspears to assist in saving Chahbek Village from certain ruin by pillagers and piratesNightfall introduced heroes in Guild Wars which are NPCs that accompany a player on their travels and fight alongside themPlayers join up with the first Hero, Koss, before embarking on the mission in Chahbek VillageThere are over 250 quests in Nightfall as well as 20 cooperative missions.

Choosing a Campaign
While the most obvious differences are the storylines, environments and professions, there are other minor differences between campaignsGaining a secondary profession is slightly different in each campaign simply because of the level at which it's learnableSecondary professions are available almost immediately in Prophecies, but players have to wait until level 5 in Nightfall to learn a secondary profession.

Each profession has corresponding available Runes and Insignias, which are used to increase a player's skills and abilities, and so these differ from one campaign to the nextPlayers can cross campaigns through a quest available on each, and therefore, choosing a campaign is merely based on personal preference of content and play styleWith all three campaigns being rich in content and beautifully constructed, any choice has the potential to be a good one.